perf kvm: introduce --list-cmds for use by scripts

Introduce

  $ perf kvm --list-cmds

to dump a raw list of commands for use by the completion script. In
order to do this, introduce parse_options_subcommand() for handling
subcommands as a special case in the parse-options machinery.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Acked-by: David Ahern <dsahern@gmail.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Link: http://lkml.kernel.org/r/1393896396-10427-1-git-send-email-artagnon@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
index a735051..21c164b 100644
--- a/tools/perf/builtin-kvm.c
+++ b/tools/perf/builtin-kvm.c
@@ -1691,17 +1691,15 @@
 		OPT_END()
 	};
 
-
-	const char * const kvm_usage[] = {
-		"perf kvm [<options>] {top|record|report|diff|buildid-list|stat}",
-		NULL
-	};
+	const char *const kvm_subcommands[] = { "top", "record", "report", "diff",
+						"buildid-list", "stat", NULL };
+	const char *kvm_usage[] = { NULL, NULL };
 
 	perf_host  = 0;
 	perf_guest = 1;
 
-	argc = parse_options(argc, argv, kvm_options, kvm_usage,
-			PARSE_OPT_STOP_AT_NON_OPTION);
+	argc = parse_options_subcommand(argc, argv, kvm_options, kvm_subcommands, kvm_usage,
+					PARSE_OPT_STOP_AT_NON_OPTION);
 	if (!argc)
 		usage_with_options(kvm_usage, kvm_options);