Add `gl_set_proc_address`

vendor/sdl3/sdl3_video.odin

@@ -455,4 +455,10 @@ foreign lib {
 	GL_GetSwapInterval              :: proc(interval: ^c.int) -> bool ---
 	GL_SwapWindow                   :: proc(window: ^Window) -> bool ---
 	GL_DestroyContext               :: proc(ctx: GLContext) -> bool ---
+}
+
+
+// Used by vendor:OpenGL
+gl_set_proc_address :: proc(p: rawptr, name: cstring) {
+	(^FunctionPointer)(p)^ = GL_GetProcAddress(name)
 }