Add a SafeMap equivalent to std::map but without the error-prone operator[].

Change-Id: Iae5ba2091c55a34dbd1005cf3d25fce2a8d5c1f9
diff --git a/src/intern_table.h b/src/intern_table.h
index bb8e031..58d87d0 100644
--- a/src/intern_table.h
+++ b/src/intern_table.h
@@ -18,11 +18,11 @@
 #define ART_SRC_INTERN_TABLE_H_
 
 #include <iosfwd>
-#include <map>
 
 #include "heap.h"
 #include "mutex.h"
 #include "object.h"
+#include "safe_map.h"
 
 namespace art {