Unescaped left brace in regex is deprecated

[bortzmeyer]

With the current git version:

% ./plugins/check_multi -f ../test-anchors.cmd
Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/^define ([a-z0-9\_\-]+) { <-- HERE $/ at ./plugins/check_multi line 1365.
OK - 4 plugins checked, 1 critical (France-IX), 1 warning (Rezopole), 2 ok
...

% perl -v

This is perl 5, version 22, subversion 0 (v5.22.0) built for armv6l-linux-thread-multi