Fix SELinux labeling for system.img

The system partition isn't getting labeled during the build.
This patch corrects that.
Signed-off-by: rpcraig <rpcraig@tycho.ncsc.mil>

Change-Id: I2695c60232935da272ac194fb9ece016c84b4593
diff --git a/ext4_utils/Android.mk b/ext4_utils/Android.mk
index 5dae31f..afa81b5 100644
--- a/ext4_utils/Android.mk
+++ b/ext4_utils/Android.mk
@@ -42,7 +42,9 @@
 LOCAL_LDLIBS += -lws2_32
 else
 ifeq ($(HAVE_SELINUX), true)
+LOCAL_C_INCLUDES += external/libselinux/include
 LOCAL_STATIC_LIBRARIES += libselinux
+LOCAL_CFLAGS += -DHAVE_SELINUX
 endif # HAVE_SELINUX
 endif