perf ui browser: Refactor the code to parse color configs with ltrim()

When parsing {fore, back} ground color configs, use ltrim() instead of
just while loop and isspace().

Signed-off-by: Taeung Song <treeze.taeung@gmail.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/1491575061-704-4-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browser.c

@@ -579,7 +579,7 @@ static int ui_browser__color_config(const char *var, const char *value,
 			break;
 
 		*bg = '\0';
-		while (isspace(*++bg));
+		bg = ltrim(++bg);
 		ui_browser__colorsets[i].bg = bg;
 		ui_browser__colorsets[i].fg = fg;
 		return 0;