android: build shared glapi

This builds the shared library libglapi from shared glapi.

Reviewed-by: Chad Versace <chad@chad-versace.us>
diff --git a/Android.mk b/Android.mk
index def8ec2..f585575 100644
--- a/Android.mk
+++ b/Android.mk
@@ -71,6 +71,7 @@
 ifneq ($(strip $(MESA_GPU_DRIVERS)),)
 
 SUBDIRS := \
+	src/mapi \
 	src/glsl \
 	src/mesa \
 	src/egl/main