Specify full paths for scripts run inside the chroot.

Remove the assumption that the current directory is ~/trunk/src/scripts/
when the chroot is entered with cros_sdk.

BUG=chromium:429765
TEST=Ran build_chromeos.py, build_tc.py with the changes.

Change-Id: I9e54fda6b5f8ec8fe18b18cf67824c923a7e82e2
Reviewed-on: https://chrome-internal-review.googlesource.com/182270
Reviewed-by: Luis Lozano <llozano@chromium.org>
Commit-Queue: Rahul Chaudhry <rahulchaudhry@google.com>
Tested-by: Rahul Chaudhry <rahulchaudhry@google.com>
diff --git a/build_tc.py b/build_tc.py
index 5419b55..ad092aa 100755
--- a/build_tc.py
+++ b/build_tc.py
@@ -1,6 +1,8 @@
 #!/usr/bin/python
 #
-# Copyright 2010 Google Inc. All Rights Reserved.
+# Copyright 2010 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
 
 """Script to build the ChromeOS toolchain.
 
@@ -50,7 +52,8 @@
         "chroot",
         "usr/local/bin/emerge-%s" % self._board)
     if not os.path.exists(cross_symlink):
-      command = "./setup_board --board=%s" % self._board
+      command = ("%s/setup_board --board=%s" %
+                 (misc.CHROMEOS_SCRIPTS_DIR, self._board))
       self._ce.ChrootRunCommand(self._chromeos_root, command)
 
   def Build(self):