dumpstate: transition into vdc domain

dumpstate uses vdc to collect asec lists and do a vold dump.
Force a transition into the vdc domain when this occurs.

Addresses the following denial:

  <4>[ 1099.623572] type=1400 audit(1403716545.565:7): avc: denied { execute } for pid=6987 comm="dumpstate" name="vdc" dev="mmcblk0p8" ino=222 scontext=u:r:dumpstate:s0 tcontext=u:object_r:vdc_exec:s0 tclass=file permissive=0

Change-Id: I4bd9f3ad83480f8c9f9843ffe136295c582f96fe