Add use_sysroot=false to Linux PDFium bots.

scripts/slave/recipes/pdfium.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 DEPS = [
   'depot_tools/gclient',
   'depot_tools/bot_update',
   'recipe_engine/path',
   'recipe_engine/platform',
   'recipe_engine/properties',
@@ skipping 37 matching lines @@
   args = [
       'is_debug=%s' % gn_bool[not rel],
       'is_component_build=false',
       'pdf_enable_v8=%s' % gn_bool[v8],
       'pdf_enable_xfa=%s' % gn_bool[xfa],
       'pdf_use_skia=%s' % gn_bool[skia],
       'pdf_is_standalone=true',
   ]
   if api.platform.is_win and not memory_tool:
     args.append('symbol_level=1')
+  if api.platform.is_linux:
+    args.append('use_sysroot=false')
   if clang:
     args.append('is_clang=true')
   if memory_tool == 'asan':
     args.append('is_asan=true')
   if target_os:
     args.append('target_os="%s"' % target_os)
   if target_cpu == 'x86':
     args.append('target_cpu="x86"')
 
   api.python('gn gen', gn_cmd,
@@ skipping 302 matching lines @@
 
   yield (
       api.test('android') +
       api.platform('linux', 64) +
       api.properties(mastername='client.pdfium',
                      buildername='android',
                      slavename='test_slave',
                      target_os='android',
                      skip_test=True)
   )