Updated tc_enter_chroot.py to create temp file that it executes later.

I noticed that the nightly client didn't go past build_tc, and it turns out
that for newer checkouts of chromeos, ./enter_chroot 'sudo ls -lt' doesn't work.
This is a workaround that allows for flexible commands to be passed in. I haven't
tested it fully but it should work for us. Have a look and I'll submit tomorrow.

PRESUBMIT=passed
R=raymes,bjanakiraman
DELTA=34  (12 added, 15 deleted, 7 changed)
OCL=45920-p2
RCL=45933-p2
RDATE=2010/12/16 10:55:17


P4 change: 42607333
3 files changed
tree: bc64631437ed097173ed12f2c01d05757e703191
  1. .git5_specs/
  2. v14/