completion: complete some 'git log' options

1. '--exclude=' option to 'git log' and 'git shortlog' are missing. Add the
option to __git_log_shortlog_options.

2. The `--committer` option in `git log` requires a pattern, such as
`--committer=ba`, but in `git shortlog`, specifying a pattern results in
an error: “error: option `committer' takes no value.” Handle them as
separate options for completion rather than a shared one.

Signed-off-by: KIYOTA Fumiya <aimluck.kiyota@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -2218,7 +2218,7 @@ __git_log_gitk_options="
 "
 # Options that go well for log and shortlog (not gitk)
 __git_log_shortlog_options="
-	--author= --committer= --grep=
+	--author= --grep= --exclude=
 	--all-match --invert-grep
 "
 # Options accepted by log and show
@@ -2296,6 +2296,7 @@ __git_complete_log_opts ()
 			$__git_log_shortlog_options
 			$__git_log_gitk_options
 			$__git_log_show_options
+			--committer=
 			--root --topo-order --date-order --reverse
 			--follow --full-diff
 			--abbrev-commit --no-abbrev-commit --abbrev=
@@ -3229,7 +3230,7 @@ _git_shortlog ()
 		__gitcomp "
 			$__git_log_common_options
 			$__git_log_shortlog_options
-			--numbered --summary --email
+			--committer --numbered --summary --email
 			"
 		return
 		;;