Merged from trunk 6039:6048

Merged from trunk 6039:6048

For bug #167667, use the existence of ${PORTDIR}/manifest1_obsolete to
trigger the disabling of manifest1/digest file generation.  This toggle
is repo/overlay specific, allowing a specific overlay to drop manifest1
buy adding the manifest1_obsolete file.

For bug #167667, add support for ${PORTDIR}/manifest1_obsolete and
automatically remove ${FILESDIR}/digest-* from cvs when appropriate.
(prefix: do the same thing for SVN)

Don't bother to parse ${FILESDIR}/digest-* when manifest1_compat is
disabled.

For bug #167668, use an rsync "hide" filter rule to exclude
**/files/digest-* and delete them on the receiver.

Remove quotes since rsync doesn't accept them (and there is no shell to
remove them since we use spawn() for rsync now).

svn path=/main/branches/prefix/; revision=6083