Add <sys/quota.h>.

It turns out that at least the Nexus 9 kernel is built without CONFIG_QUOTA.
If we decide we're going to mandate quota functionality, I'm happy for us to
be a part of CTS that ensures that happens, but I don't want to be first, so
there's not much to test here other than "will it compile?". The strace
output looks right though.

Bug: http://b/27948821
Bug: http://b/27952303
Change-Id: If667195eee849ed17c8fa9110f6b02907fc8fc04
diff --git a/tests/Android.mk b/tests/Android.mk
index 7fdf2f4..3e8c1a7 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -102,6 +102,7 @@
     sys_personality_test.cpp \
     sys_prctl_test.cpp \
     sys_procfs_test.cpp \
+    sys_quota_test.cpp \
     sys_resource_test.cpp \
     sys_select_test.cpp \
     sys_sendfile_test.cpp \