Add legacy layout support to FUSE, enforce write.

The legacy internal layout places users at the top-level of the
filesystem, so handle with new PERM_LEGACY_PRE_ROOT when requested.

Mirror single OBB directory between all users without requiring fancy
bind mounts by letting a nodes graft in another part of the
underlying tree.

Move to everything having "sdcard_r" GID by default, and verify that
calling apps hold "sdcard_rw" when performing mutations. Determines
app group membership from new packages.list column.

Flag to optionally enable sdcard_pics/sdcard_av permissions
splitting. Flag to supply a default GID for all files. Ignore
attempts to access security sensitive files. Fix run-as to check for
new "package_info" GID.

Change-Id: Id5f3680779109141c65fb8fa1daf56597f49ea0d
diff --git a/run-as/package.c b/run-as/package.c
index 27fc1eb..4762c5f 100644
--- a/run-as/package.c
+++ b/run-as/package.c
@@ -111,7 +111,7 @@
         goto EXIT;
 
     /* Ensure that the file is owned by the system user */
-    if ((st.st_uid != AID_SYSTEM) || (st.st_gid != AID_SYSTEM)) {
+    if ((st.st_uid != AID_SYSTEM) || (st.st_gid != AID_PACKAGE_INFO)) {
         goto EXIT;
     }