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
diff --git a/v14/build_tc.py b/v14/build_tc.py
index d1578fb..a488cf6 100755
--- a/v14/build_tc.py
+++ b/v14/build_tc.py
@@ -165,7 +165,7 @@
 
 
 def CreateEnvVarString(variable, value):
-  return "export " + variable + "=\"" + value + "\"; "
+  return variable + "=\"" + value + "\""
 
 
 def EscapeQuoteString(string):
@@ -225,7 +225,8 @@
                 " --gcc " + gcc_version +
                 " --kernel " + kernel_version +
                 crossdev_flags)
-    command = (" " + env + " cp -r $(portageq envvar PKGDIR)/* /var/lib/portage/pkgs/")
+    command += ("&& sudo cp -r $(" + env + " portageq envvar PKGDIR)/*" +
+                " /var/lib/portage/pkgs/")
 
   argv = [rootdir + "/tc_enter_chroot.py",
           "--chromeos_root=" + chromeos_root,