mac_tool.py: Handle non-zero ibtool return code.

Without check_output() the Popen() will always return None as returncode, this
prevents error handling during the build process.

With check_output() it will raise an exception in case of non-zero return code.

BUG=None

Change-Id: I911b7f65d9f58240893ed96d1170e5544f534278
Reviewed-on: https://chromium-review.googlesource.com/548400
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>

pylib/gyp/mac_tool.py

@@ -105,17 +105,21 @@ def _CopyXIBFile(self, source, dest):
 
     ibtool_section_re = re.compile(r'/\*.*\*/')
     ibtool_re = re.compile(r'.*note:.*is clipping its content')
-    ibtoolout = subprocess.Popen(args, stdout=subprocess.PIPE)
+    try:
+      stdout = subprocess.check_output(args)
+    except subprocess.CalledProcessError as e:
+      print(e.output)
+      raise
     current_section_header = None
-    for line in ibtoolout.stdout:
+    for line in stdout.splitlines():
       if ibtool_section_re.match(line):
         current_section_header = line
       elif not ibtool_re.match(line):
         if current_section_header:
-          sys.stdout.write(current_section_header)
+          print(current_section_header)
           current_section_header = None
-        sys.stdout.write(line)
-    return ibtoolout.returncode
+        print(line)
+    return 0
 
   def _ConvertToBinary(self, dest):
     subprocess.check_call([