Fix presubmit script for .cc files which include system files first.

PRESUBMIT.py

Index: PRESUBMIT.py
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 7cbfa4474df12fa36aa647673531da79d4d6652f..5616d94fd3f34d8a066fc34e5db97bd698e46211 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -690,7 +690,6 @@ def _CheckIncludeOrderForScope(scope, input_api, file_path, changed_linenums):
   2. C++ system files in alphabetical order
   3. Project's .h files
   """
-
   c_system_include_pattern = input_api.re.compile(r'\s*#include <.*\.h>')
   cpp_system_include_pattern = input_api.re.compile(r'\s*#include <.*>')
   custom_include_pattern = input_api.re.compile(r'\s*#include ".*')
@@ -775,6 +774,8 @@ def _CheckIncludeOrderInFile(input_api, f, changed_linenums):
 
   for line in contents:
     line_num += 1
+    if uncheckable_includes_pattern.match(line):
+      continue
     if system_include_pattern.match(line):
       # No special first include -> process the line again along with normal
       # includes.