Set the default compiler for X87 to GCC.

build/standalone.gypi

 # 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 128 matching lines @@
             'fastbuild': 1,
           }],
         ],
       }],
       ['(v8_target_arch=="ia32" or v8_target_arch=="x64" or v8_target_arch=="x87") and \
         (OS=="linux" or OS=="mac")', {
         'v8_enable_gdbjit%': 1,
       }, {
         'v8_enable_gdbjit%': 0,
       }],
-      ['(OS=="linux" or OS=="mac") and (target_arch=="ia32" or target_arch=="x64")', {
+      ['(OS=="linux" or OS=="mac") and (target_arch=="ia32" or target_arch=="x64") and \
+        (v8_target_arch!="x87")', {
         'clang%': 1,
       }, {
         'clang%': 0,
       }],
       ['host_arch!="ppc" and host_arch!="ppc64" and host_arch!="ppc64le"', {
         'host_clang%': '1',
       }, {
         'host_clang%': '0',
       }],
     ],
@@ skipping 422 matching lines @@
     ['use_goma==1 and ("<(GENERATOR)"=="ninja" or clang==1)', {
       'make_global_settings': [
        ['CC_wrapper', '<(gomadir)/gomacc'],
        ['CXX_wrapper', '<(gomadir)/gomacc'],
        ['CC.host_wrapper', '<(gomadir)/gomacc'],
        ['CXX.host_wrapper', '<(gomadir)/gomacc'],
       ],
     }],
   ],
 }