[build] Prepare removal of gyp-defines from landmine

Depends on: https://crrev.com/c/924114

TBR=yangguo@chromium.org

Bug: chromium:756691
Change-Id: Ibbc3bd35e8727296c1539edc961e3184830575ff
Reviewed-on: https://chromium-review.googlesource.com/924609Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51341}

tools/get_landmines.py

@@ -8,17 +8,8 @@ This file emits the list of reasons why a particular build needs to be clobbered
 (or a list of 'landmines').
 """
 
-import os
 import sys
 
-SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))
-CHECKOUT_ROOT = os.path.abspath(os.path.join(SCRIPT_DIR, os.pardir))
-sys.path.insert(0, os.path.join(CHECKOUT_ROOT, 'build'))
-import landmine_utils
-
-
-platform = landmine_utils.platform  # pylint: disable=invalid-name
-
 
 def print_landmines():  # pylint: disable=invalid-name
   """