perf tools: Use single strcmp call instead of two

There's no need to use 2 strcmp calls, one is enough.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1417460789-13874-2-git-send-email-jolsa@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/config.c

@@ -522,7 +522,7 @@ static int buildid_dir_command_config(const char *var, const char *value,
 	const char *v;
 
 	/* same dir for all commands */
-	if (!prefixcmp(var, "buildid.") && !strcmp(var + 8, "dir")) {
+	if (!strcmp(var, "buildid.dir")) {
 		v = perf_config_dirname(var, value);
 		if (!v)
 			return -1;