valgrind: have MappedLockBytes take complete ownership of the file handle

have MappedLockBytes take complete ownership of the file handle and
unmap it and close it on release. Otherwise xFile will close it
and MappedLockBytes will unmap it in that order, which breaks
post android requirement to have a valid file handle in unmap

store/source/lockbyte.cxx

@@ -509,6 +509,7 @@ struct FileMapping
     static void unmapFile (oslFileHandle hFile, sal_uInt8 * pAddr, sal_uInt32 nSize)
     {
         (void) osl_unmapMappedFile (hFile, pAddr, nSize);
+        (void) osl_closeFile (hFile);
     }
 
     /** @see ResourceHolder<T>::destructor_type
@@ -922,6 +923,7 @@ FileLockBytes_createInstance (
             rxLockBytes = new MappedLockBytes (xMapping.get());
             if (!rxLockBytes.is())
                 return store_E_OutOfMemory;
+            (void) xFile.release();
             (void) xMapping.release();
         }
     }