vold: Fix devmapper/ptmx fd leak, and give asec unmount more time

Signed-off-by: San Mehat <san@google.com>
diff --git a/Devmapper.cpp b/Devmapper.cpp
index 9dd8ef3..800ee69 100644
--- a/Devmapper.cpp
+++ b/Devmapper.cpp
@@ -167,6 +167,7 @@
 
     free(buffer);
 
+    close(fd);
     return 0;
 }