client: Remove assumptions about the contents of cfg/
client: Remove assumptions about the contents of cfg/

- Don't choke if a directory is present in cache/cfg or last/cfg.  This
fixes a bug triggered when vmplayer 2 crashes and leaves a stale lockdir in
cfg/.

- Remove stale files in last/cfg when copying it from cache/cfg during
"isr sync".  This fixes a bug which would cause a stale memory image
to be used after the following sequence of operations:

1. Shut down parcel
2. isr sync parcel
3. isr discard parcel
4. isr resume parcel

(cherry picked from commit a37276de5b47eedb663e5f1ef545cb29f8c2c69a)
(cherry picked from commit 22cc3155ff08b452fc89493ff7da5cb93a3f4528)

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr