EmuGL: refinements to GLESv1 image_external

* EGLImageTargetRenderbufferStorageOES was incorrectly accepting
  TEXTURE_EXTERNAL_OES as a target. Revert that; the host GL will
  correctly reject it with INVALID_ENUM.

* Handle the REQUIRED_TEXTURE_IMAGE_UNITS_OES texparameter query.

* Validate texture parameters set on TEXTURE_EXTERNAL textures;
  otherwise invalid parameters would work on the emulator but not on a
  real device.

Change-Id: I49a088608d58a9822f33e5916bd354eee3709127
2 files changed