[perl #40911] [CAGE] Merge manifest generating scripts with mk_manifest_and_skip.pl

[Paul Cochrane]

# New Ticket Created by Paul Cochrane
# Please include the string: [perl #40911]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=40911 >

The functionality of tools/dev/gen_manifest_skip.pl and
tools/dev/mk_manifests.pl could be merged into
mk_manifest_and_skip.pl, these files can then be removed. Note: check
all references to the files before removing them. The ack tool (via
App::Ack on CPAN) is very helpful with this task.