perf tools: Factorize the map helpers

Factorize the dso mapping helpers into a single purpose common file
"util/map.c"

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Brice Goglin <Brice.Goglin@inria.fr>

tools/perf/util/callchain.h

@@ -4,6 +4,7 @@
 #include "../perf.h"
 #include <linux/list.h>
 #include <linux/rbtree.h>
+#include "util.h"
 #include "symbol.h"
 
 enum chain_mode {