android: gallium/freedreno: add preliminary build

android: gallium/freedreno: add preliminary build

For all the people interested in testing the freedreno driver on
their Android devices. The next commit will hook these up within
the libEGL driver (via the gallium-egl backend).

There may be some rough edges but those can be sorted when a
willing builder/tester comes along.

v2:
 - s/freefreno/freedreno/. Spotted by Matt Turner.
 - Use the installed libdrm headers.

Cc: "10.1 10.2" <mesa-stable@lists.freedesktop.org>
Cc: Rob Clark <robclark@freedesktop.org>
Cc: freedreno@lists.freedesktop.org
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>