Note that threads is currently customized in blead
Fix various "CPAN only" warnings for cpan/ modules in Porting/Maintainers.pl
Create bit for /n.
Fixes to make test pass for regexp nocapture bit addition.

 * Make Devel-Peek/t/Peek.t less sensitive to regexp flag changes.

   Devel-Peek had flag names and binary representation hardcoded. Flag
   names *should* be enough. Otherwise we have to update bits of this
   test every time we muck with flags that don't affect the flags being
   tested.

 * Let B::Deparse know about the new RXf_PMf_CHARSET shift value.
Support for nocapture regexp flag /n

This flag will prevent () from capturing and filling in $1, $2, etc...

Named captures will still work though, and if used will cause $1, $2, etc...
to be filled in *only* within named groups.

The motivation behind this is to allow the common construct of:

  /(?:b|c)a(?:t|n)/

To be rewritten more cleanly as:

  /(b|c)a(t|n)/n

When you want grouping but no memory penalty on captures.

You can also use ?n inside of a () directly to avoid capturing, and
?-n inside of a () to negate its effects if you want to capture.
Bump re.pm version for changes
Add tests for stringification of regexps containing /n
Remove inactive CUSTOMIZED entry.
pp.c:pp_rand: Only EXTEND when not popping
pp.c:pp_rv2sv: Use >= instead of switch

This results in smaller machine code.

If a freed SV is exposed to perl space then ${\$freed} will now die,
which is arguably more correct.
pp.c:pp_pos: Less stack fiddling

We always pop exactly one item off the stack and then push exactly one
item.  Instead of doing sp-- and sp++, just leave it alone (TOP/SET,
rather than POP/PUSH).  Also skip PUTBACK, which is unnecessary.
pp.c:pp_rv2cv: Remove PUTBACK

pp_rv2cv doesn’t adjust the stack pointer at all, so there is no need
to synchronise with the global pointer before returning.
pp.c:pp_srefgen: Remove PUTBACK

We don’t manipulate the stack pointer at all here.
Don’t write beyond the stack with scalar \()
[perl #123514] Make prototype() imply $_

Previously it would read and replace the previous item on the stack:

$ ./perl -le 'print "CORE::undef", prototype'
;\[$@%&*]
perlfunc: prototype implies $_
Remove ‘require Config’ from ref.t

82b84d04879 removed the code that needed it.
pp.c:pp_gelem: Less stack fiddling

Instead of pop, pop, push, just do one pop and then replace the
remaining item.  Also, there is no need to extend the stack here, as
pp_gelem returns fewer items than it consumes.
pp.c:pp_study: Less stack fiddling

We always pop and push exactly one item.  We can skip the sp++ and
sp--, and also the PUTBACK.
Fix bad write in pp_trans

y/// has not been extending the stack for lexical $_, even since lex-
ical $_ was added.  $lexical =~ y/// has not been extending the stack
since v5.21.5-339-g05a502d.