--gl_debug flag.

src/xenia/gpu/gl4/gl4_gpu.cc

@@ -19,6 +19,7 @@ DEFINE_bool(disable_gl_context_reset, false,
             "Do not aggressively reset the GL context (helps with capture "
             "programs such as OBS or FRAPS).");
 
+DEFINE_bool(gl_debug, false, "Enable OpenGL debug validation layer.");
 DEFINE_bool(gl_debug_output, false, "Dump ARB_debug_output to stderr.");
 DEFINE_bool(gl_debug_output_synchronous, true,
             "ARB_debug_output will synchronize to be thread safe.");