doc-patch & test-patch for `perl -V:<name>`

folks,

V-config-pod-rex   
    adds pod wrt  regex feature of -V:name
    I resisted any commentary on implementation, ex what triggers 
literal vs regex search.
    (arguably regex could do literal..)

V-config-t-rexdos
       adds 3 tests to verify that a regex like /.*(?{ `rm -rf / ` })/  
is prevented.

It has a couple todo tests, one of which appears to expose a bug.
I was unable to search RT for a possible match, and google showed only 1 
near fit
from 15k hits on this: perl "Sequence (?{...})" regex.

uncommenting the print in the t-patch yields:

res: Sequence (?{...}) not terminated or not {}-balanced in regex; 
marked by <-- HERE in m/^abuse.*(?{ <-- HERE =/ at ../lib/Config.pm line 
1244.
Attempt to free unreferenced scalar: SV 0x81a488c.

• doc-patch & test-patch for `perl -V:<name>` by Jim Cromie
• Re: doc-patch & test-patch for `perl -V:<name>` by hv