Used prebuilt OpenAL library for Windows build because MinGW lacks mu…

…tex support needed to compile OpenAL.

CMakeLists.txt

@@ -300,33 +300,15 @@ if(MINGW AND CMAKE_CROSSCOMPILING)
         ${CMAKE_CURRENT_SOURCE_DIR}/extern/sdl2/i686-w64-mingw32/lib/libSDL2.dll.a
     )
 
+    set(OPENAL_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/extern/openal/include/AL")
+    set(OPENAL_LIBRARY ${CMAKE_CURRENT_SOURCE_DIR}/extern/openal/libs/Win32/OpenAL32.lib)
+
     set(CMAKE_EXE_LINKER_FLAGS "-static-libgcc -static-libstdc++")
 else()
     find_package(OpenAL REQUIRED)
     find_package(SDL2 REQUIRED)
 endif()
 
-# Detect system OpenAL (SDL2 must be already defined)
-
-if (FORCE_SYSTEM_OPENAL)
-    find_package(OpenAL QUIET)
-    if (NOT OPENAL_FOUND)
-        message("System-provided OpenAL not found. Enabling internal OpenAL support.")
-        set(OPENTOMB_INTERNAL_OPENAL ON)
-    else()
-        set(OPENTOMB_INTERNAL_OPENAL OFF)
-    endif ()
-else ()
-    set(OPENTOMB_INTERNAL_OPENAL ON)
-endif ()
-
-if (OPENTOMB_INTERNAL_OPENAL)
-    add_subdirectory(extern/openal)
-    set(OPENAL_INCLUDE_DIR "${CMAKE_CURRENT_SOURCE_DIR}/extern/openal/include/AL")
-    set(OPENAL_LIBRARY OpenAL32)
-endif ()
-find_package(OpenAL REQUIRED)
-
 set(OPENTOMB_ICON "resource/icon/opentomb.rc")
 
 # Check for optional OpenAL include files that are not present in all implementations of the library