intltool-update trips over Perl 5.26's sctricter regex syntax

[Dave Brown]

    $ intltool-update
    Unescaped left brace in regex is illegal here in regex; marked by <-- HERE in m/^(.*)\${ <--HERE ?([A-Z_]+)}?(.*)$/ at /usr/bin/intltool-update line 1065.
    $ perl -v

    This is perl 5, version 26, subversion 0 (v5.26.0) built for x86_64-linux-thread-multi

    Copyright 1987-2017, Larry Wall

    Perl may be copied only under the terms of either the Artistic License or the
    GNU General Public License, which may be found in the Perl 5 source kit.

    Complete documentation for Perl, including FAQ lists, should be found on
    this system using "man perl" or "perldoc perl". If you have access to the
    Internet, point your browser at http://www.perl.org/, the Perl Home Page.

If it's trying to match an actual literal ${ (as in, a dollar sign followed by a curly bracket), I'd suggest changing
    /\${...}/
throughout intltool-update's code to
    /\$\{...\}/