Remove (untested) code for unsupported compilers.

tools/gyp/v8.gyp

 # Copyright 2012 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 1424 matching lines @@
               'conditions': [
                 ['build_env=="Cygwin"', {
                   'sources': [
                     '../../src/base/platform/platform-cygwin.cc',
                     '../../src/base/platform/platform-posix.cc'
                   ],
                 }, {
                   'sources': [
                     '../../src/base/platform/platform-win32.cc',
                     '../../src/base/win32-headers.h',
-                    '../../src/base/win32-math.cc',
-                    '../../src/base/win32-math.h'
                   ],
                 }],
               ],
               'link_settings':  {
                 'libraries': [ '-lwinmm', '-lws2_32' ],
               },
             }, {
               'sources': [
                 '../../src/base/platform/platform-win32.cc',
                 '../../src/base/win32-headers.h',
-                '../../src/base/win32-math.cc',
-                '../../src/base/win32-math.h'
               ],
               'msvs_disabled_warnings': [4351, 4355, 4800],
               'link_settings':  {
                 'libraries': [ '-lwinmm.lib', '-lws2_32.lib' ],
               },
             }],
           ],
         }],
       ],
     },
@@ skipping 254 matching lines @@
         }],
         ['v8_compress_startup_data=="bz2"', {
           'libraries': [
             '-lbz2',
           ]
         }],
       ],
     },
   ],
 }