Don't check message compiler results for .mc files

message_compiler.py checks to make sure its results match those
generated by mc.exe, but these checks are only valid for a given version
of mc.exe, because the output changes with every new Windows 10 SDK
version. The checking is disabled for SDK versions other than 10.0.15063
but only for .man files. This change extends the disabling of checking
for .mc files also, due to observed failures.

Bug: 774669
Change-Id: I618f68d8926b73621192e7933aea5d264fedd214
Reviewed-on: https://chromium-review.googlesource.com/807205Reviewed-by: Scott Graham <scottmg@chromium.org>
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Cr-Commit-Position: refs/heads/master@{#521577}

build/win/message_compiler.py

@@ -55,11 +55,12 @@ def main():
   env_pairs = open(env_file).read()[:-2].split('\0')
   env_dict = dict([item.split('=', 1) for item in env_pairs])
 
-  if input_file.endswith('.man'):
+  extension = os.path.splitext(input_file)[1]
+  if extension in ['.man', '.mc']:
     # For .man files, mc's output changed significantly from Version 10.0.15063
     # to Version 10.0.16299.  We should always have the output of the current
     # default SDK checked in and compare to that. Early out if a different SDK
-    # is active.
+    # is active. This also happens with .mc files.
     # TODO(thakis): Check in new baselines and compare to 16299 instead once
     # we use the 2017 Fall Creator's Update by default.
     mc_help = subprocess.check_output(['mc.exe', '/?'], env=env_dict,