Remove mentions of EGL_ANDROID_image_crop

This extension was initially a hack to fix a hardware problem on the
Nexus 4. It is undocumented and no current hardware implements it in
its EGL driver. Remove all code that interacts with it.

Bug: b/15287899
Test: Pixel XL boots
Change-Id: I28d4899537a587dda694feb11eaf3e7c7a2ab0a5