perf annotate browser: Align jump labels

Find out at browser startup the max width and use it when rendering jump
labels on the screen.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-7dxjiwqb77wz6f5lc05e0i0x@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/util.c

@@ -148,3 +148,13 @@ int readn(int fd, void *buf, size_t n)
 
 	return buf - buf_start;
 }
+
+size_t hex_width(u64 v)
+{
+	size_t n = 1;
+
+	while ((v >>= 4))
+		++n;
+
+	return n;
+}