Disable surfaceless context support

Using surfaceless EGL surface on imx6 embedded device
crashes webengine with backtrace in gpu driver.
Since this feature requires a bit more testing on
embedded platforms disable support for the 5.7.1 release.

Task-number: QTBUG-57290
Change-Id: I3ed5b6fc173d184486316a2c3d899a88d4b1de76
Reviewed-by: Allan Sandfeld Jensen <[email protected]>

Author: Michal Klocek

src/core/gl_surface_qt.cpp

@@ -365,7 +365,8 @@ bool GLSurfaceQtEGL::InitializeOneOff()
         LOG(ERROR) << "eglInitialize failed with error " << GetLastEGLErrorString();
         return false;
     }
-
+#if 0
+// QTBUG-57290
     g_egl_surfaceless_context_supported = ExtensionsContain(g_extensions, "EGL_KHR_surfaceless_context");
     if (g_egl_surfaceless_context_supported) {
         scoped_refptr<GLSurface> surface = new GLSurfacelessQtEGL(Size(1, 1));
@@ -382,7 +383,7 @@ bool GLSurfaceQtEGL::InitializeOneOff()
             context->ReleaseCurrent(surface.get());
         }
     }
-
+#endif
     initialized = true;
     return true;
 }