Replace the previous OpenGL loader with a glad-generated 3.3 one

The main advantage of switching to glad from glLoadGen is that, apart
from being actively maintained, it supports a customizable entrypoint
loader function, which makes it possible to also support OpenGL ES.

src/citra/CMakeLists.txt

@@ -15,7 +15,7 @@ create_directory_groups(${SRCS} ${HEADERS})
 
 add_executable(citra ${SRCS} ${HEADERS})
 target_link_libraries(citra core video_core common)
-target_link_libraries(citra ${GLFW_LIBRARIES} ${OPENGL_gl_LIBRARY} inih)
+target_link_libraries(citra ${GLFW_LIBRARIES} ${OPENGL_gl_LIBRARY} inih glad)
 if (MSVC)
     target_link_libraries(citra getopt)
 endif()
@@ -23,4 +23,4 @@ target_link_libraries(citra ${PLATFORM_LIBRARIES})
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "Linux|FreeBSD|OpenBSD|NetBSD")
     install(TARGETS citra RUNTIME DESTINATION "${CMAKE_INSTALL_PREFIX}/bin")
-endif()
+endif()

src/citra/emu_window/emu_window_glfw.cpp

@@ -7,7 +7,7 @@
 #include <string>
 
 // Let’s use our own GL header, instead of one from GLFW.
-#include "video_core/renderer_opengl/generated/gl_3_2_core.h"
+#include <glad/glad.h>
 #define GLFW_INCLUDE_NONE
 #include <GLFW/glfw3.h>