perf: Use format string of printf to align strings

Instead of filling whitespaces to do alignment, use
printf's format string.

This simplifies the code a bit.
Signed-off-by: NWANG Cong <amwang@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091214082700.4224.57640.sendpatchset@localhost.localdomain>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

tools/perf/builtin-help.c

@@ -286,8 +286,7 @@ void list_common_cmds_help(void)
 
 	puts(" The most commonly used perf commands are:");
 	for (i = 0; i < ARRAY_SIZE(common_cmds); i++) {
-		printf("   %s   ", common_cmds[i].name);
-		mput_char(' ', longest - strlen(common_cmds[i].name));
+		printf("   %-*s   ", longest, common_cmds[i].name);
 		puts(common_cmds[i].help);
 	}
 }