data/scripts: rackup now has an unversioned interpreter

Signed-off-by: Niels Thykier <niels@thykier.net>
d/common/source-fields: Add "dgit" field

Signed-off-by: Niels Thykier <niels@thykier.net>
c/cruft.pm: Refactor gfdl detection

Instead of using a variable for space like expression, tranform every
space like expression to space.

This is a net win of about 5% on execution time

[nthykier:
 * realign some regexes/comments to work around perltidy
 * replace regex with $str eq ''
]

Signed-off-by: Niels Thykier <niels@thykier.net>
c/cruft.pm: Silent false positive in po file of gtk-doc

Gtk-doc use some <_:link-1> for no invariant section. Silent this
false positive.

Signed-off-by: Niels Thykier <niels@thykier.net>
c/cruft.pm: Remove the last word in a regex

Signed-off-by: Niels Thykier <niels@thykier.net>
d/changelog: Add changelog entry for #721252

Signed-off-by: Niels Thykier <niels@thykier.net>