perf tools: Introduce struct maps

That for now has the maps rbtree and the list for the dead maps, that
may be still referenced from some hist_entry, etc.

This paves the way for protecting the rbtree with a lock, then refcount
the maps and finally remove the removed_maps list, as it'll not ne
anymore needed.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-fl0fa6142pj8khj97fow3uw0@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b9e3eb5..c8a3e79 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -202,7 +202,7 @@
 
 void __map_groups__fixup_end(struct map_groups *mg, enum map_type type)
 {
-	struct rb_root *maps = &mg->maps[type];
+	struct maps *maps = &mg->maps[type];
 	struct map *next, *curr;
 
 	curr = maps__first(maps);
@@ -1520,7 +1520,7 @@
 struct map *map_groups__find_by_name(struct map_groups *mg,
 				     enum map_type type, const char *name)
 {
-	struct rb_root *maps = &mg->maps[type];
+	struct maps *maps = &mg->maps[type];
 	struct map *map;
 
 	for (map = maps__first(maps); map; map = map__next(map)) {