fs_mgr: Small fix in overlayfs setup/teardown

In user builds, we fix fs_mgr_overlayfs_{setup,teardown} to
properly set the optional 'change' boolean, if it was provided.

Test: TreeHugger
Change-Id: I91fc99d801f8fd782b21f0ecaecddfc7744f0c3e
diff --git a/fs_mgr/fs_mgr_overlayfs.cpp b/fs_mgr/fs_mgr_overlayfs.cpp
index bafa2b3..74dfc00 100644
--- a/fs_mgr/fs_mgr_overlayfs.cpp
+++ b/fs_mgr/fs_mgr_overlayfs.cpp
@@ -49,12 +49,12 @@
 }
 
 bool fs_mgr_overlayfs_setup(const char*, const char*, bool* change) {
-    if (change) change = false;
+    if (change) *change = false;
     return false;
 }
 
 bool fs_mgr_overlayfs_teardown(const char*, bool* change) {
-    if (change) change = false;
+    if (change) *change = false;
     return false;
 }