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>

Android.mk

@@ -24,7 +24,7 @@
 # BOARD_GPU_DRIVERS should be defined.  The valid values are
 #
 #   classic drivers: i915 i965
-#   gallium drivers: swrast i915g ilo nouveau r300g r600g radeonsi vmwgfx
+#   gallium drivers: swrast freedreno i915g ilo nouveau r300g r600g radeonsi vmwgfx
 #
 # The main target is libGLES_mesa.  For each classic driver enabled, a DRI
 # module will also be built.  DRI modules will be loaded by libGLES_mesa.
@@ -42,7 +42,7 @@ DRM_TOP := external/drm
 DRM_GRALLOC_TOP := hardware/drm_gralloc
 
 classic_drivers := i915 i965
-gallium_drivers := swrast i915g ilo nouveau r300g r600g radeonsi vmwgfx
+gallium_drivers := swrast freedreno i915g ilo nouveau r300g r600g radeonsi vmwgfx
 
 MESA_GPU_DRIVERS := $(strip $(BOARD_GPU_DRIVERS))