git: support --list-cmds=list-<category>

This allows us to select any group of commands by a category defined
in command-list.txt. This is an internal/hidden option so we don't
have to be picky about the category name or worried about exposing too
much.

This will be used later by git-completion.bash to retrieve certain
command groups.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

generate-cmdlist.sh

@@ -45,6 +45,21 @@ define_categories () {
 	test "$bit" -gt 32 && die "Urgh.. too many categories?"
 }
 
+define_category_names () {
+	echo
+	echo "/* Category names */"
+	echo "static const char *category_names[] = {"
+	bit=0
+	category_list "$1" |
+	while read cat
+	do
+		echo "	\"$cat\", /* (1UL << $bit) */"
+		bit=$(($bit+1))
+	done
+	echo "	NULL"
+	echo "};"
+}
+
 print_command_list () {
 	echo "static struct cmdname_help command_list[] = {"
 
@@ -70,4 +85,6 @@ struct cmdname_help {
 "
 define_categories "$1"
 echo
+define_category_names "$1"
+echo
 print_command_list "$1"