op.c: Remove dummy code from const_sv_xsub

This was added in commit 9cbac4c7 with no explanation.  It has been
#ifdeffed out since it was added.  That commit was supposedly just for
compiler warnings.  I think this was something else the author was
playing with that got combined in the same patch by mistake.
Revert "Make t/podcheck.t less sensitive"

This reverts commit f26da014a698383ac348973050af3e754752e6ab.

Conflicts:
	t/porting/known_pod_issues.dat
do not worry about long verbatim lines w/o env var

To run these tests, set PERL_POD_PEDANTIC in the environment.

This needs further testing, at least, to ensure that it behaves correctly
when regenerating the known problem files.
Run the pedantic checks when regenerating the database

Make the two checks of possible poor uses of C<>
pedantic checks.

Allow --pedantic to turn on those tests in addition to
the environmnt variable.
regenerate t/porting/known_pod_issues.dat