[NaCl SDK] Make mono buildbot script run in the proper directory.

Changes to the annotator required launching the script differently.

BUG=none
TEST=nacl mono buildbots

Review URL: https://chromiumcodereview.appspot.com/10829266

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@150925 0039d316-1c4b-4281-b951-d872f2087c98

native_client_sdk/src/build_tools/nacl-mono-buildbot.py

@@ -160,6 +160,8 @@ def main(args):
   buildbot_revision = os.environ.get('BUILDBOT_REVISION', '')
   buildername = os.environ.get('BUILDBOT_BUILDERNAME', '')
 
+  os.chdir(buildbot_common.SCRIPT_DIR)
+
   if buildername == 'linux-sdk-mono32':
     assert buildbot_revision
     sdk_revision = buildbot_revision.split(':')[0]