Sync with Git 2.20.1

* maint: Git 2.20.1 .gitattributes: ensure t/oid-info/* has eol=lf t9902: 'send-email' test case requires PERL t4256: mark support files as LF-only parse-options: fix SunCC compiler warning help -a: handle aliases with long names gracefully help.h: fix coding style run-command: report exec failure