fix core-cpan-diff treatment of 'undef'
Update Maintainers.PL for divergence from cpan

I've noted some files customized in blead and marked
Devel::PPPort as 'undef' upstream as it appears unmaintained
and rjbs has asked the maintainer to switch it to blead.

With this change, core-cpan-diff on the 'cpan' upstream is clean.
t/porting/customized.t: consistent data file sorting
bump Time::Piece VERSION to 1.2002
Rough draft of perldelta for v5.19.1

Added some things that were missing; deleted lots of boilerplate and
unused sections.

Module updates are not done, as Module::CoreList needs updating first.
Acknowlegements are not done, either.
add some tests for Perl #71922

Apparently this is fixed now. But add tests
Fix Perl version references in INSTALL

Also update the RMG to remind people to do this for the "late" bumps in
BLEAD-POINT and BLEAD-FINAL releases
portport: remove DG/UX
update Module::CoreList for v5.19.1 release
update perlhist for v5.19.1
finalize perldelta.pod for v5.19.1
add cpan/autodie/t/truncate_me to makerel @writables list
Porting/epigraphs.pod: add v5.19.1 and v5.19.0 epigraphs
new perldelta
bump version to v5.19.2
stub Module::CoreList for v5.19.2
Benchmark.t: fix skip() argument order
Porting/epigraphs.pod: add link to release announcement
Revert "portport: remove DG/UX"

This reverts commit 28371e3dbee6234e13f1dfa4afb650ba7691ebfc.
perldiag: Document ‘Can't call mro_method_changed_in()’