Merge branch 'ab/simplify-perl-makefile'

The build procedure for perl/ part has been greatly simplified by
weaning ourselves off of MakeMaker.

* ab/simplify-perl-makefile:
  perl: treat PERLLIB_EXTRA as an extra path again
  perl: avoid *.pmc and fix Error.pm further
  Makefile: replace perl/Makefile.PL with simple make rules

git-send-email.perl

@@ -26,7 +26,7 @@ use Text::ParseWords;
 use Term::ANSIColor;
 use File::Temp qw/ tempdir tempfile /;
 use File::Spec::Functions qw(catdir catfile);
-use Error qw(:try);
+use Git::Error qw(:try);
 use Cwd qw(abs_path cwd);
 use Git;
 use Git::I18N;