GN Windows build fixes

build/toolchain/win/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 declare_args() {
   # Path to the directory containing the VC binaries for the right
   # combination of host and target architectures. Currently only the
   # 64-bit host toolchain is supported, with either 32-bit or 64-bit targets.
   # If vc_bin_dir is not specified on the command line (and it normally
   # isn't), we will dynamically determine the right value to use at runtime.
@@ skipping 83 matching lines @@
       rspfile = "{{output}}.rsp"
 
       # The PDB name needs to be different between C and C++ compiled files.
       pdbname = "{{target_out_dir}}/{{target_output_name}}_cc.pdb"
       command = "ninja -t msvc -e $env -- $cl /nologo /showIncludes /FC @$rspfile /c {{source}} /Fo{{output}} /Fd$pdbname"
       depsformat = "msvc"
       description = "CXX {{output}}"
       outputs = [
         "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.obj",
       ]
-      rspfile_content = "{{defines}} {{include_dirs}} {{cflags}} {{cflags_c}}"
+      rspfile_content = "{{defines}} {{include_dirs}} {{cflags}} {{cflags_cc}}"
     }
 
     tool("rc") {
       command = "$python_path gyp-win-tool rc-wrapper $env rc.exe {{defines}} {{include_dirs}} /fo{{output}} {{source}}"
       outputs = [
         "{{source_out_dir}}/{{target_output_name}}.{{source_name_part}}.res",
       ]
       description = "RC {{output}}"
     }
 
@@ skipping 102 matching lines @@
   }
 }
 
 if (current_cpu == "x64") {
   msvc_toolchain("64") {
     environment = "environment.x64"
 
     current_cpu = "x64"
   }
 }