[coverage] Enable sanitizer coverage.

build/coverage_wrapper.py

 #!/usr/bin/env python
 # Copyright 2016 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # CC/CXX wrapper script that excludes certain file patterns from coverage
 # instrumentation.
 
 import re
 import subprocess
 import sys
 
 exclusions = [
+  'buildtools',
   'src/third_party',
   'third_party',
   'test',
   'testing',
 ]
 
+def remove_if_exists(string_list, item):
+  try:

[kjellander_chromium, 2016/03/08 04:48:33]

I guess it's faster to do
if item in string_list:
  string_list.remove(item)
instead of allowing an exception to be thrown? Assuming exceptions are as
expensive as in C++ and Java. Not a big deal here though, but if you want :)

[Michael Achenbach, 2016/03/08 10:05:46]

Done. Your way is definitely more readable and I don't care for speed here. This
is bounded by the number of objects, which are max 1000 for v8. And each list
contains maybe ~30 items.

[tandrii(chromium), 2016/03/08 14:48:57]

Your honor, I object! First, 
try .. except ValueError: .. 
is the Pythonic way to do stuff.
Second, here each line takes O(n):
1) if x in list
2)   list.remove(x)

So, there is no way try..catch is slower than code above.

[Michael Achenbach, 2016/03/08 14:53:59]

Right. Either way, I think it's hardly measurable given the small number of
objects. Maybe I change to more pythonic again in next CL.

+    string_list.remove(item)
+  except:
+    pass
+
 args = sys.argv[1:]
 text = ' '.join(sys.argv[2:])
 for exclusion in exclusions:
   if re.search(r'\-o obj/%s[^ ]*\.o' % exclusion, text):
-    args.remove('-fprofile-arcs')
-    args.remove('-ftest-coverage')
+    remove_if_exists(args, '-fprofile-arcs')
+    remove_if_exists(args, '-ftest-coverage')
+    remove_if_exists(args, '-fsanitize-coverage=func')
+    remove_if_exists(args, '-fsanitize-coverage=bb')
+    remove_if_exists(args, '-fsanitize-coverage=edge')
     break
 
 sys.exit(subprocess.check_call(args))