Establish explicit dependency on selinux file_contexts.

Before this change, because the file_contexts is not in the system,
data or cache directory, the dependency is not reliable.
This fixed the gms build error:
out/target/product/gms/root/file_contexts: No such file or directory

Change-Id: Id8d5b3f4557d43a509ccc00b21dd426a414b7c42
1 file changed