Split NAME line on multiple whitespaces

Split NAME line on multiple whitespaces

For:  RT # 133683

pod/perlmodlib.pod is a file generated by pod/perlmodlib.PL, which is
run by 'miniperl' during 'make'.  That program parses the 'NAME' header
of .pod files and fragments of POD found in 'regen/opcode.pl'.  The POD
for B::Op_private is one such fragment.  Correcting a superfluous
whitespace in that fragment did not suffice to prevent the downstream
formatting error reported in the RT -- an error visible with 'pod2text'
and 'pod2html' as well.  We also had to make the regex which
perlmodlib.PL uses to parse the 'NAME' header more flexible.