gsdx-ogl: windows: properly setup context flags

* Use a core profile context
* Only enable the debug context in debug build

Close issue #353

plugins/GSdx/GSWndWGL.cpp

@@ -57,7 +57,10 @@ bool GSWndWGL::CreateContext(int major, int minor)
 			// FIXME : Request a debug context to ease opengl development
 			// Note: don't support deprecated feature (pre openg 3.1)
 			//GLX_CONTEXT_FLAGS_ARB, GLX_CONTEXT_DEBUG_BIT_ARB | GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB,
+#ifdef ENABLE_OGL_DEBUG
 			WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_DEBUG_BIT_ARB,
+#endif
+			WGL_CONTEXT_PROFILE_MASK_ARB, WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
 			0
 		};