perf stat: Refactor the code to strip csv output with ltrim()

To strip csv output, use ltrim() instead of just while loop and
isspace() at print_metric_{only}_csv().

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/1491575061-704-3-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-stat.c

@@ -875,10 +875,7 @@ static void print_metric_csv(void *ctx,
 		return;
 	}
 	snprintf(buf, sizeof(buf), fmt, val);
-	vals = buf;
-	while (isspace(*vals))
-		vals++;
-	ends = vals;
+	ends = vals = ltrim(buf);
 	while (isdigit(*ends) || *ends == '.')
 		ends++;
 	*ends = 0;
@@ -950,10 +947,7 @@ static void print_metric_only_csv(void *ctx, const char *color __maybe_unused,
 		return;
 	unit = fixunit(tbuf, os->evsel, unit);
 	snprintf(buf, sizeof buf, fmt, val);
-	vals = buf;
-	while (isspace(*vals))
-		vals++;
-	ends = vals;
+	ends = vals = ltrim(buf);
 	while (isdigit(*ends) || *ends == '.')
 		ends++;
 	*ends = 0;