Fix resizing of shm apps

Change-Id: Iad94691317bde38603d9143f951b1b69326ab12e
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Don't create an invalidated surface when not needed

After invalidateSurface() is called we don't want to recreate
the EGLSurface on setGeometry() until makeCurrent is called

Change-Id: Ide10ecf3bff40a01fa1ed249986a631c77c2bf63
Merge pull request #5 from giucam/fixes

Fixes when resizing egl windows