Unset some environment vars so they can be set up via the bisect script.

BUG=
NOTRY=true

Review URL: https://chromiumcodereview.appspot.com/18991015

git-svn-id: http://src.chromium.org/svn/trunk/src/build@211214 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

android/buildbot/bb_host_steps.py

@@ -100,8 +100,7 @@ def BisectPerfRegression(_):
   RunCmd([SrcPath('tools', 'prepare-bisect-perf-regression.py'),
           '-w', os.path.join(constants.DIR_SOURCE_ROOT, os.pardir)])
   RunCmd([SrcPath('tools', 'run-bisect-perf-regression.py'),
-          '-w', os.path.join(constants.DIR_SOURCE_ROOT, os.pardir),
-          '-p', bb_utils.GOMA_DIR])
+          '-w', os.path.join(constants.DIR_SOURCE_ROOT, os.pardir)])
 
 
 def GetHostStepCmds():