i915: build i915_dri.so for Android

Simple demos such as test-opengl-gl_basic work.  SurfaceFlinger does not
work yet due to missing GL_OES_draw_texture support (and maybe more).

Reviewed-by: Chad Versace <chad@chad-versace.us>
diff --git a/Android.mk b/Android.mk
index 7c7c55a..a5c9ebc 100644
--- a/Android.mk
+++ b/Android.mk
@@ -23,7 +23,7 @@
 
 # BOARD_GPU_DRIVERS should be defined.  The valid values are
 #
-#   classic drivers: i965
+#   classic drivers: i915 i965
 #   gallium drivers: swrast i915g nouveau r300g r600g vmwgfx
 #
 # The main target is libGLES_mesa.  For each classic driver enabled, a DRI
@@ -36,7 +36,7 @@
 DRM_TOP := external/drm
 DRM_GRALLOC_TOP := hardware/drm_gralloc
 
-classic_drivers := i965
+classic_drivers := i915 i965
 gallium_drivers := swrast i915g nouveau r300g r600g vmwgfx
 
 MESA_GPU_DRIVERS := $(strip $(BOARD_GPU_DRIVERS))