Replace linux-specific code in test scripts.

testing/tools/run_pixel_tests.py

 #!/usr/bin/env python
 # Copyright 2015 The PDFium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import optparse
 import os
 import re
 import subprocess
 import sys
@@ skipping 14 matching lines @@
                       fixup_path, pdfium_test_path, pdfium_diff_path):
   input_root, _ = os.path.splitext(input_filename)
   input_path = os.path.join(source_dir, input_root + '.in')
   pdf_path = os.path.join(working_dir, input_root + '.pdf')
   actual_path_template = os.path.join(working_dir, input_root + '.pdf.%d.png')
   expected_path_template = os.path.join(source_dir,
                                         input_root + '_expected.pdf.%d.png')
   try:
     sys.stdout.flush()
     subprocess.check_call(
-        [fixup_path, '--output-dir=' + working_dir, input_path])
+        [sys.executable, fixup_path, '--output-dir=' + working_dir, input_path])
     subprocess.check_call([pdfium_test_path, '--png', pdf_path])
     i = 0;
     while True:
       expected_path = expected_path_template % i;
       actual_path = actual_path_template % i;
       if not os.path.exists(expected_path):
         if i == 0:
           print "WARNING: no expected results files found for " + input_filename
         break
       print "Checking " + actual_path
@@ skipping 90 matching lines @@
 
   if failures:
     print '\n\nSummary of Failures:'
     for failure in failures:
       print failure
     return 1
   return 0
 
 if __name__ == '__main__':
   sys.exit(main())