bitbake/cooker: Ensure matchFile returns full pathnames

bitbake/cooker: Ensure matchFile returns full pathnames

We should always be passing full pathnames around within bitbake. If
a file was referenced as a relative path to the current working
directory, it might not get passed through the abspath call and
hence the cwd would not get added as a prefix.

This change adds a second pass at ensuring we only return absolute paths.

(Bitbake rev: 72fc62ca124a24e2dbe404a3c83a49608a7c7931)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>