Log Message:
Import p5-Regexp-Parser version 0.20.

Should fix PR#39541.

This module parses regular expressions (regexes). Its default \ 
"grammar" is Perl
5.8.4's regex set. Grammar is quoted because the module does not so much define
a grammar as let each matched node state what it expects to match next, but
there is not currently a way of extracting a complete grammar. This may change
in future versions.