Fix mac build

Disable memunreachable_test for mac.

Change-Id: Ie9594b6e5dfc661c4d709b419dbcb7b610434a84
(cherry picked from commit e33686b7cad8169ba799f2348d86a670b4224220)
diff --git a/libmemunreachable/Android.mk b/libmemunreachable/Android.mk
index 8421fcc..7b66d44 100644
--- a/libmemunreachable/Android.mk
+++ b/libmemunreachable/Android.mk
@@ -60,5 +60,6 @@
 LOCAL_CFLAGS := -std=c++14 -Wall -Wextra -Werror
 LOCAL_CLANG := true
 LOCAL_SHARED_LIBRARIES := libbase liblog
+LOCAL_MODULE_HOST_OS := linux
 
 include $(BUILD_HOST_NATIVE_TEST)