Implement C++11 move semantics for android::FileMap

FileMaps should be movable, thereby not requiring them to be only used
with a unique_ptr as they currently are.

Change-Id: I0fb8013bf398a2ced5420d85ba888c2a7fc5a496
diff --git a/include/utils/FileMap.h b/include/utils/FileMap.h
index afd7bfd..7d372e1 100644
--- a/include/utils/FileMap.h
+++ b/include/utils/FileMap.h
@@ -52,6 +52,9 @@
 public:
     FileMap(void);
 
+    FileMap(FileMap&& f);
+    FileMap& operator=(FileMap&& f);
+
     /*
      * Create a new mapping on an open file.
      *