platform/sdl: workaround ubuntu SDL2 bug preventing resolving any extensions on EGL

engine/platform/sdl/vid_sdl.c

@@ -438,6 +438,25 @@ GL_GetProcAddress
 void *GL_GetProcAddress( const char *name )
 {
 	void *func = SDL_GL_GetProcAddress( name );
+#if !SDL_VERSION_ATLEAST( 2, 0, 6 ) && XASH_POSIX
+	if( !func && Sys_CheckParm( "-egl" ))
+	{
+		/*
+		 * SDL2 has broken SDL_GL_GetProcAddress until this commit if using egl:
+		 * https://github.com/libsdl-org/SDL/commit/466ba57d42d244e80357e9ad3011c50af30ed225
+		 * so call eglGetProcAddress directly
+		 * */
+		static void *(*peglGetProcAddress)( const char * );
+		if( !peglGetProcAddress )
+		{
+			void *lib = dlopen( "libEGL.so", RTLD_NOW );
+			if( lib )
+				*(void**)&peglGetProcAddress = dlsym( lib, "eglGetProcAddress" );
+		}
+		if( peglGetProcAddress )
+			func = peglGetProcAddress( name );
+	}
+#endif
 
 #if XASH_PSVITA
 	// try to find in main module