Merge-from-Googlecode r419

Merge-from-Googlecode r419

In archive_write_disk:  If archive_write_header() fails to create
the file, that's a failure and should return ARCHIVE_FAILED.
Metadata restore failures still return ARCHIVE_WARN, because
that's non-critical.  Fix test_write_disk_secure test to
verify the correct return code in one case; add test_write_disk_failures
to do another very simple test of restore failure.

This should fix cpio coredumping when it tries to restore to
a write-protected directory.

Thanks to: Giorgos Keramidas
MFC after: 30 days