Merges .go-sdl2-libs as part of the repository (#392)

This fixes static and/or cross-platform build when using the new Go
Module system as it doesn't fetch the (previously) sub-module
go-sdl2-libs.

Signed-off-by: Lilis Iskandar <lilis@veand.co>

.go-sdl2-libs/include/SDL2/SDL.h

@@ -0,0 +1,135 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ *  \file SDL.h
+ *
+ *  Main include header for the SDL library
+ */
+
+
+#ifndef SDL_h_
+#define SDL_h_
+
+#include "SDL_main.h"
+#include "SDL_stdinc.h"
+#include "SDL_assert.h"
+#include "SDL_atomic.h"
+#include "SDL_audio.h"
+#include "SDL_clipboard.h"
+#include "SDL_cpuinfo.h"
+#include "SDL_endian.h"
+#include "SDL_error.h"
+#include "SDL_events.h"
+#include "SDL_filesystem.h"
+#include "SDL_gamecontroller.h"
+#include "SDL_haptic.h"
+#include "SDL_hints.h"
+#include "SDL_joystick.h"
+#include "SDL_loadso.h"
+#include "SDL_log.h"
+#include "SDL_messagebox.h"
+#include "SDL_mutex.h"
+#include "SDL_power.h"
+#include "SDL_render.h"
+#include "SDL_rwops.h"
+#include "SDL_sensor.h"
+#include "SDL_shape.h"
+#include "SDL_system.h"
+#include "SDL_thread.h"
+#include "SDL_timer.h"
+#include "SDL_version.h"
+#include "SDL_video.h"
+
+#include "begin_code.h"
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* As of version 0.5, SDL is loaded dynamically into the application */
+
+/**
+ *  \name SDL_INIT_*
+ *
+ *  These are the flags which may be passed to SDL_Init().  You should
+ *  specify the subsystems which you will be using in your application.
+ */
+/* @{ */
+#define SDL_INIT_TIMER          0x00000001u
+#define SDL_INIT_AUDIO          0x00000010u
+#define SDL_INIT_VIDEO          0x00000020u  /**< SDL_INIT_VIDEO implies SDL_INIT_EVENTS */
+#define SDL_INIT_JOYSTICK       0x00000200u  /**< SDL_INIT_JOYSTICK implies SDL_INIT_EVENTS */
+#define SDL_INIT_HAPTIC         0x00001000u
+#define SDL_INIT_GAMECONTROLLER 0x00002000u  /**< SDL_INIT_GAMECONTROLLER implies SDL_INIT_JOYSTICK */
+#define SDL_INIT_EVENTS         0x00004000u
+#define SDL_INIT_SENSOR         0x00008000u
+#define SDL_INIT_NOPARACHUTE    0x00100000u  /**< compatibility; this flag is ignored. */
+#define SDL_INIT_EVERYTHING ( \
+                SDL_INIT_TIMER | SDL_INIT_AUDIO | SDL_INIT_VIDEO | SDL_INIT_EVENTS | \
+                SDL_INIT_JOYSTICK | SDL_INIT_HAPTIC | SDL_INIT_GAMECONTROLLER | SDL_INIT_SENSOR \
+            )
+/* @} */
+
+/**
+ *  This function initializes  the subsystems specified by \c flags
+ */
+extern DECLSPEC int SDLCALL SDL_Init(Uint32 flags);
+
+/**
+ *  This function initializes specific SDL subsystems
+ *
+ *  Subsystem initialization is ref-counted, you must call
+ *  SDL_QuitSubSystem() for each SDL_InitSubSystem() to correctly
+ *  shutdown a subsystem manually (or call SDL_Quit() to force shutdown).
+ *  If a subsystem is already loaded then this call will
+ *  increase the ref-count and return.
+ */
+extern DECLSPEC int SDLCALL SDL_InitSubSystem(Uint32 flags);
+
+/**
+ *  This function cleans up specific SDL subsystems
+ */
+extern DECLSPEC void SDLCALL SDL_QuitSubSystem(Uint32 flags);
+
+/**
+ *  This function returns a mask of the specified subsystems which have
+ *  previously been initialized.
+ *
+ *  If \c flags is 0, it returns a mask of all initialized subsystems.
+ */
+extern DECLSPEC Uint32 SDLCALL SDL_WasInit(Uint32 flags);
+
+/**
+ *  This function cleans up all initialized subsystems. You should
+ *  call it upon all exit conditions.
+ */
+extern DECLSPEC void SDLCALL SDL_Quit(void);
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include "close_code.h"
+
+#endif /* SDL_h_ */
+
+/* vi: set ts=4 sw=4 expandtab: */

.go-sdl2-libs/include/SDL2/SDL2_framerate.h

@@ -0,0 +1,100 @@
+/*
+
+SDL2_framerate.h: framerate manager
+
+Copyright (C) 2012-2014  Andreas Schiffler
+
+This software is provided 'as-is', without any express or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not
+claim that you wrote the original software. If you use this software
+in a product, an acknowledgment in the product documentation would be
+appreciated but is not required.
+
+2. Altered source versions must be plainly marked as such, and must not be
+misrepresented as being the original software.
+
+3. This notice may not be removed or altered from any source
+distribution.
+
+Andreas Schiffler -- aschiffler at ferzkopp dot net
+
+*/
+
+#ifndef _SDL2_framerate_h
+#define _SDL2_framerate_h
+
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+	/* --- */
+
+#include "SDL.h"
+
+	/* --------- Definitions */
+
+	/*!
+	\brief Highest possible rate supported by framerate controller in Hz (1/s).
+	*/
+#define FPS_UPPER_LIMIT		200
+
+	/*!
+	\brief Lowest possible rate supported by framerate controller in Hz (1/s).
+	*/
+#define FPS_LOWER_LIMIT		1
+
+	/*!
+	\brief Default rate of framerate controller in Hz (1/s).
+	*/
+#define FPS_DEFAULT		30
+
+	/*! 
+	\brief Structure holding the state and timing information of the framerate controller. 
+	*/
+	typedef struct {
+		Uint32 framecount;
+		float rateticks;
+		Uint32 baseticks;
+		Uint32 lastticks;
+		Uint32 rate;
+	} FPSmanager;
+
+	/* ---- Function Prototypes */
+
+#ifdef _MSC_VER
+#  if defined(DLL_EXPORT) && !defined(LIBSDL2_GFX_DLL_IMPORT)
+#    define SDL2_FRAMERATE_SCOPE __declspec(dllexport)
+#  else
+#    ifdef LIBSDL2_GFX_DLL_IMPORT
+#      define SDL2_FRAMERATE_SCOPE __declspec(dllimport)
+#    endif
+#  endif
+#endif
+#ifndef SDL2_FRAMERATE_SCOPE
+#  define SDL2_FRAMERATE_SCOPE extern
+#endif
+
+	/* Functions return 0 or value for sucess and -1 for error */
+
+	SDL2_FRAMERATE_SCOPE void SDL_initFramerate(FPSmanager * manager);
+	SDL2_FRAMERATE_SCOPE int SDL_setFramerate(FPSmanager * manager, Uint32 rate);
+	SDL2_FRAMERATE_SCOPE int SDL_getFramerate(FPSmanager * manager);
+	SDL2_FRAMERATE_SCOPE int SDL_getFramecount(FPSmanager * manager);
+	SDL2_FRAMERATE_SCOPE Uint32 SDL_framerateDelay(FPSmanager * manager);
+
+	/* --- */
+
+	/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+
+#endif				/* _SDL2_framerate_h */