Extend white-listed directories to include /mnt/expand

Apps on sdcard live under /mnt/expand and therefore
this directory should be under linker namespaces
permitted_path.

Bug: http://b/28639227
Change-Id: I462f9f23656c95d9c2a48bb3f513abcd9d08f340
(cherry picked from commit f334cbf0e1425633bef96a21b0ce9e30f4c6ffa9)
1 file changed