[Android] Fall back to using dlsym on ourselves to pull in OpenGL Fun…

…ctions when eglGetProcAddress fails. This fixes an issue on the Chromebook where I was forced to link to libGLESv2 and pull in the functions statically since eglGetProcAddress wouldn't return any GLESv3 functions. This also changes glMapBuffer to glMapBufferOES because glMapBuffer isn't actually part of the OpenGL ES 3 spec...

Source/Plugins/Plugin_VideoOGL/Src/GLFunctions.cpp

@@ -3,6 +3,7 @@
 // Refer to the license.txt file included.
 #include "GLFunctions.h"
 #include "Log.h"
+#include <dlfcn.h>
 #ifdef USE_GLES3
 PFNGLMAPBUFFERPROC glMapBuffer;
 PFNGLMAPBUFFERRANGEPROC glMapBufferRange;
@@ -43,27 +44,35 @@ PFNGLGENQUERIESPROC glGenQueries;
 #endif
 namespace GLFunc
 {
+	void *self;
 	void LoadFunction(const char *name, void **func)
 	{
 #ifdef USE_GLES3
 		*func = (void*)eglGetProcAddress(name);
 		if (*func == NULL)
 		{
-			ERROR_LOG(VIDEO, "Couldn't load function %s", name);
-			exit(0);
+			// Fall back to trying dlsym
+			if (self) // Just in case dlopen fails
+				*func = dlsym(self, name);
+			if (*func == NULL)
+			{
+				ERROR_LOG(VIDEO, "Couldn't load function %s", name);
+				exit(0);
+			}
 		}
 #endif
 	}
 
 	void Init()
 	{
+		self = dlopen(NULL, RTLD_LAZY);
 		LoadFunction("glBeginQuery", (void**)&glBeginQuery);
 		LoadFunction("glEndQuery", (void**)&glEndQuery);
 		LoadFunction("glGetQueryObjectuiv", (void**)&glGetQueryObjectuiv);
 		LoadFunction("glDeleteQueries", (void**)&glDeleteQueries);
 		LoadFunction("glGenQueries", (void**)&glGenQueries);
 		{
-			LoadFunction("glMapBuffer", (void**)&glMapBuffer);	
+			LoadFunction("glMapBufferOES", (void**)&glMapBuffer);	
 			LoadFunction("glUnmapBuffer", (void**)&glUnmapBuffer);
 			LoadFunction("glMapBufferRange", (void**)&glMapBufferRange);
 			LoadFunction("glBindBufferRange", (void**)&glBindBufferRange);
@@ -93,5 +102,6 @@ namespace GLFunc
 
 		LoadFunction("glGetUniformBlockIndex", (void**)&glGetUniformBlockIndex);
 		LoadFunction("glUniformBlockBinding", (void**)&glUniformBlockBinding);
+		dlclose(self);
 	}
 }