Override product_extension instead of product_version to set SONAME for Linux shared library

tools/gyp/v8.gyp

 # Copyright 2011 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 54 matching lines @@
                   'defines': [
                     'V8_SHARED',
                   ],
                   'direct_dependent_settings': {
                     'defines': [
                       'V8_SHARED',
                     ],
                   },
                 }],
                 ['soname_version!=""', {
-                  # Ideally, we'd like to specify the full filename for the
-                  # library and set it to "libv8.so.<(soname_version)",
-                  # but currently the best we can do is use 'product_name' and
-                  # get "libv8-<(soname_version).so".
-                  'product_name': 'v8-<(soname_version)',
+                  'product_extension': 'so.<(soname_version)',
                 }],
               ],
             },
             {
               'type': 'none',
             }],
           ],
           'direct_dependent_settings': {
             'include_dirs': [
               '../../include',
@@ skipping 810 matching lines @@
             }],
           ],
           'dependencies': [
             'v8'
           ],
         },
       ],
     }],
   ],
 }