android: fix undefined references to futex API

Fixes: f98a2768ca "mesa: Add new fast mtx_t mutex type for basic use cases"
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
diff --git a/Android.common.mk b/Android.common.mk
index 103e3fe..d9f871c 100644
--- a/Android.common.mk
+++ b/Android.common.mk
@@ -69,6 +69,7 @@
 	-DHAVE_PTHREAD=1 \
 	-DHAVE_DLADDR \
 	-DHAVE_DL_ITERATE_PHDR \
+	-DHAVE_LINUX_FUTEX_H \
 	-DMAJOR_IN_SYSMACROS \
 	-fvisibility=hidden \
 	-Wno-sign-compare