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

Documentation/RelNotes/2.20.1.txt

@@ -0,0 +1,20 @@
+Git v2.20.1 Release Notes
+=========================
+
+This release is primarily to fix brown-paper-bag breakages in the
+2.20.0 release.
+
+Fixes since v2.20
+-----------------
+
+ * A few newly added tests were not portable and caused minority
+   platforms to report false breakages, which have been fixed.
+
+ * Portability fix for a recent update to parse-options API.
+
+ * "git help -a" did not work well when an overly long alias is
+   defined, which has been corrected.
+
+ * A recent update accidentally squelched an error message when the
+   run_command API failed to run a missing command, which has been
+   corrected.