perf diff: Color the Ratio column

In

  $ perf diff -c ratio

color the Ratio column using value_color_snprintf(), a new function that
operates exactly like percent_color_snprintf().

At first glance, it looks like percent_color_snprintf() can be turned
into a non-variadic function simplifying things; however, 53805ec (perf
tools: Remove cast of non-variadic function to variadic, 2013-10-31)
explains why it needs to be a variadic function.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/1388388861-7931-4-git-send-email-artagnon@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/color.c b/tools/perf/util/color.c
index 8cda46c..87b8672 100644
--- a/tools/perf/util/color.c
+++ b/tools/perf/util/color.c
@@ -319,15 +319,19 @@
 	return r;
 }
 
+int value_color_snprintf(char *bf, size_t size, const char *fmt, double value)
+{
+	const char *color = get_percent_color(value);
+	return color_snprintf(bf, size, color, fmt, value);
+}
+
 int percent_color_snprintf(char *bf, size_t size, const char *fmt, ...)
 {
 	va_list args;
 	double percent;
-	const char *color;
 
 	va_start(args, fmt);
 	percent = va_arg(args, double);
 	va_end(args);
-	color = get_percent_color(percent);
-	return color_snprintf(bf, size, color, fmt, percent);
+	return value_color_snprintf(bf, size, fmt, percent);
 }