make: Support '#' characters in defines.

pylib/gyp/generator/make.py

 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # Notes:
 #
 # This is all roughly based on the Makefile system used by the Linux
 # kernel, but is a non-recursive make -- we put the entire dependency
 # graph in front of make and let it figure it out.
 #
@@ skipping 565 matching lines @@
 def EscapeMakeVariableExpansion(s):
   """Make has its own variable expansion syntax using $. We must escape it for
      string to be interpreted literally."""
   return s.replace('$', '$$')
 
 
 def EscapeCppDefine(s):
   """Escapes a CPP define so that it will reach the compiler unaltered."""
   s = EscapeShellArgument(s)
   s = EscapeMakeVariableExpansion(s)
-  return s
+  # '#' characters must be escaped even embedded in a string, else Make will
+  # treat it as the start of a comment.
+  return s.replace('#', r'\#')
 
 
 def QuoteIfNecessary(string):
   """TODO: Should this ideally be replaced with one or more of the above
      functions?"""
   if '"' in string:
     string = '"' + string.replace('"', '\\"') + '"'
   return string
 
 
@@ skipping 1531 matching lines @@
     root_makefile.write("  include " + include_file + "\n")
     root_makefile.write("endif\n")
   root_makefile.write('\n')
 
   if generator_flags.get('auto_regeneration', True):
     WriteAutoRegenerationRule(params, root_makefile, makefile_name, build_files)
 
   root_makefile.write(SHARED_FOOTER)
 
   root_makefile.close()