[perl #123410] sort CORE::fake bizarre behaviour

This commit:

commit 01b5ef509f2ebf466fd7de2c1e7406717bb14332
Author: Father Chrysostomos <sprout@cpan.org>
Date:   Fri Jun 7 20:16:23 2013 -0700

    [perl #24482] Fix sort and require to treat CORE:: as keyword

caused sort CORE::lc "FOO" to be equivalent to sort +CORE::lc "FOO",
the way it does if a keyword is not preceded by CORE::.  But it made
the mistake of chopping off the last six characters if it is not a
keyword after CORE::.

So

    sort CORE::f @_

became equivalent to

    sort C @_

!

This commit just reverts to the previous behaviour in such cases.
diag.t: Ignore trailing whitespace

If we don’t ignore trailing whitespace after ); then we end up search-
ing for the next ); in the file and skip the next message if the );
belongs to it.
Sort perldiag

I put an entry in the wrong place in 2a9203e94.
Squash some B::PADNAME methods together

COP_SEQ_RANGE_LOW and PARENT_PAD_INDEX are identical.  So are
COP_SEQ_RANGE_HIGH and PARENT_FAKELEX_FLAGS.  Don’t bother creating
four separate CVs, just two.
B::PADNAMELIST::REFCNT can be an ALIAS