Iteration on multi-user external storage.

Zygote now mounts a tmpfs over any existing /storage contents, giving
it a clean slate for its bind mounts.  This supports a symlink that
enables legacy /sdcard paths for shell users.  Move to using paths
defined from environment variables, instead of header files.

Bug: 6925012
Change-Id: Ia4a2ac35ecfe98b617c27ff3bd73deb29e395e55
1 file changed