gsdx-gl: use CONTEXT_FLAG_NO_ERROR_BIT_KHR to reduce driver overheard

Didn't test it yet as my driver is too old.

Note: might break the open source drivers.

plugins/GSdx/GLLoader.h

@@ -26,6 +26,10 @@
 #define GL_FB_DEFAULT  (0)
 #define GL_BUFFER_0    (0)
 
+#ifndef GL_CONTEXT_FLAG_NO_ERROR_BIT_KHR
+#define GL_CONTEXT_FLAG_NO_ERROR_BIT_KHR  0x00000008
+#endif
+
 // FIX compilation issue with Mesa 10
 // Note it might be possible to do better with the right include
 // in the rigth order but I don't have time

plugins/GSdx/GSWndEGL.cpp

@@ -39,6 +39,9 @@ void GSWndEGL::CreateContext(int major, int minor)
 		EGL_CONTEXT_MINOR_VERSION_KHR, minor,
 #ifdef ENABLE_OGL_DEBUG
 		EGL_CONTEXT_FLAGS_KHR, EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR,
+#else
+		// Open Source isn't happy with an unsupported flags...
+		//EGL_CONTEXT_FLAGS_KHR, GL_CONTEXT_FLAG_NO_ERROR_BIT_KHR,
 #endif
 		EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR, EGL_CONTEXT_OPENGL_CORE_PROFILE_BIT_KHR,
 		EGL_NONE

plugins/GSdx/GSWndOGL.cpp

@@ -81,6 +81,9 @@ void GSWndOGL::CreateContext(int major, int minor)
 		GLX_CONTEXT_MINOR_VERSION_ARB, minor,
 #ifdef ENABLE_OGL_DEBUG
 		GLX_CONTEXT_FLAGS_ARB, GLX_CONTEXT_DEBUG_BIT_ARB,
+#else
+		// Open Source isn't happy with an unsupported flags...
+		//GLX_CONTEXT_FLAGS_ARB, GL_CONTEXT_FLAG_NO_ERROR_BIT_KHR,
 #endif
 		GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_CORE_PROFILE_BIT_ARB,
 		None

plugins/GSdx/GSWndWGL.cpp

@@ -77,6 +77,8 @@ bool GSWndWGL::CreateContext(int major, int minor)
 			WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB
 #ifdef ENABLE_OGL_DEBUG
 			| WGL_CONTEXT_DEBUG_BIT_ARB
+#else
+			| GL_CONTEXT_FLAG_NO_ERROR_BIT_KHR
 #endif
 			,
 			WGL_CONTEXT_PROFILE_MASK_ARB, WGL_CONTEXT_CORE_PROFILE_BIT_ARB,