perf tools: Fix time function double declaration with glibc

It's enough to include the local "debug.h" file to trigger it.

man time reveals this is already declared in glibc:

time - get time in seconds
-> rename the variable.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: arjan@infradead.org
LPU-Reference: <1295620209-13859-2-git-send-email-trenn@suse.de>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/svghelper.c

@@ -44,11 +44,11 @@ static double cpu2y(int cpu)
 	return cpu2slot(cpu) * SLOT_MULT;
 }
 
-static double time2pixels(u64 time)
+static double time2pixels(u64 __time)
 {
 	double X;
 
-	X = 1.0 * svg_page_width * (time - first_time) / (last_time - first_time);
+	X = 1.0 * svg_page_width * (__time - first_time) / (last_time - first_time);
 	return X;
 }