qemu: Add an option to remove host sdl/gl checking

qemu: Add an option to remove host sdl/gl checking

Add an PACKAGECONFIG in qemu to disable GL acceleration:
* By default configure try best to enable GL acceleration and fail when missing
  host dependency(libSDL and libGL).
* End user can also choose to turn off GL capability, thus remove the host
  dependence in building.

[YOCTO #2407] got fixed.

(From OE-Core rev: cfa93553e17057a1ea9d81e3a415fc8260c54067)

Signed-off-by: Zhai Edwin <edwin.zhai@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>