completion: add show --color-moved[-ws]

The completion for diff command was added in fd0bc17557 but
missed the show command which also supports --color-moved[-ws].

This suffers from the very same problem [1] as the referenced
commit: no comma-separated list completion for --color-moved-ws.

[1]: https://github.com/scop/bash-completion/issues/240

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -2907,6 +2907,14 @@ _git_show ()
 		__gitcomp "$__git_diff_submodule_formats" "" "${cur##--submodule=}"
 		return
 		;;
+	--color-moved=*)
+		__gitcomp "$__git_color_moved_opts" "" "${cur##--color-moved=}"
+		return
+		;;
+	--color-moved-ws=*)
+		__gitcomp "$__git_color_moved_ws_opts" "" "${cur##--color-moved-ws=}"
+		return
+		;;
 	--*)
 		__gitcomp "--pretty= --format= --abbrev-commit --no-abbrev-commit
 			--oneline --show-signature --patch