Clean up attribute arrays flags in OpenGL glyph cache

When used in the SceneGraph we're expected to disable the arrays
after we're done, otherwise we'll get a warning about memory corruption
and crashes.

Change-Id: Ie8e426309716bef4b75d79039e8ca0b4943c79e7
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>

src/gui/opengl/qopengltextureglyphcache.cpp

@@ -269,6 +269,9 @@ void QOpenGLTextureGlyphCache::resizeTextureData(int width, int height)
     if (pex != 0) {
         glViewport(0, 0, pex->width, pex->height);
         pex->updateClipScissorTest();
+    } else {
+        m_blitProgram->disableAttributeArray(int(QT_VERTEX_COORDS_ATTR));
+        m_blitProgram->disableAttributeArray(int(QT_TEXTURE_COORDS_ATTR));
     }
 }