QOpenGLFramebufferObject: pass sized format also with dynamic GL

The GL_RGBA8_OES define is not in scope for dynamic OpenGL builds, so
pass in GL_RGBA8 instead (it is defined as the same value, 0x8058) when
in ES mode. The functionality check already ensures the extension is
available, so the ifdef guards can be removed.

This fixes default multisampled FBO creation under ANGLE when using
-opengl dynamic.

Task-number: QTBUG-40921
Change-Id: Iac4b7e230a463c27b61af75c3307421f9deac856
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

src/gui/opengl/qopenglframebufferobject.cpp

@@ -479,11 +479,9 @@ void QOpenGLFramebufferObjectPrivate::init(QOpenGLFramebufferObject *, const QSi
         GLenum storageFormat = internal_format;
         // ES requires a sized format. The older desktop extension does not. Correct the format on ES.
         if (ctx->isOpenGLES() && internal_format == GL_RGBA) {
-#ifdef GL_RGBA8_OES
             if (funcs.hasOpenGLExtension(QOpenGLExtensions::Sized8Formats))
-                storageFormat = GL_RGBA8_OES;
+                storageFormat = GL_RGBA8;
             else
-#endif
                 storageFormat = GL_RGBA4;
         }