Improvements for Android:

* All Linux targets: add minimal ioctl support for the ION_IOC family

* Android targets: change proprietary-ioctl support for GPUs from
  being a build-time #define kludge to being controlled by --kernel-variant,
  as it should be.  Update documentation accordingly.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14440 a5019735-40e9-0310-863c-91ae7b9d1cf9