Merge branch 'km/send-email-getopt-long-workarounds' into maint

Even though we officially haven't dropped Perl 5.8 support, the Getopt::Long package that came with it does not support "--no-" prefix to negate a boolean option; manually add support to help people with older Getopt::Long package. * km/send-email-getopt-long-workarounds: git-send-email.perl: support no- prefix with older GetOptions