android: Depend on gallium_dri from EGL, instead of linking in gallium.

android: Depend on gallium_dri from EGL, instead of linking in gallium.

The Android gallium build used to use gallium_egl, which was removed back
in March.  Instead, we will now use a normal Mesa libEGL loader with
dlopen()ing of a DRI module.

v2: add a clean step to rebuild all dri modules properly.
v3: Squish the 2 patches doing this together (change by anholt).

Signed-off-by: Chih-Wei Huang <cwhuang@linux.org.tw>
Reviewed-by: Eric Anholt <eric@anholt.net>