Merge branch 'ab/perl-fixes' into next

Clean-up to various pieces of Perl code we have.

* ab/perl-fixes:
perl Git::LoadCPAN: emit better errors under NO_PERL_CPAN_FALLBACKS
Makefile: add NO_PERL_CPAN_FALLBACKS knob
perl: move the perl/Git/FromCPAN tree to perl/FromCPAN
perl: generalize the Git::LoadCPAN facility
perl: move CPAN loader wrappers to another namespace
perl: update our copy of Mail::Address
perl: update our ancient copy of Error.pm
git-send-email: unconditionally use Net::{SMTP,Domain}
Git.pm: hard-depend on the File::{Temp,Spec} modules
gitweb: hard-depend on the Digest::MD5 5.8 module
Git.pm: add the "use warnings" pragma
Git.pm: remove redundant "use strict" from sub-package
perl: *.pm files should not have the executable bit

diff --cc Makefile
Simple merge

diff --cc git-send-email.perl
Simple merge

diff --cc perl/Git.pm
Simple merge