Add "soname_version" parameter to common.gypi, v8.gyp, Makefile

build/common.gypi

 # 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 @@
     # Enable profiling support. Only required on Windows.
     'v8_enable_prof%': 0,
 
     # Chrome needs this definition unconditionally. For standalone V8 builds,
     # it's handled in build/standalone.gypi.
     'want_separate_host_toolset%': 1,
 
     'v8_use_snapshot%': 'true',
     'host_os%': '<(OS)',
     'v8_use_liveobjectlist%': 'false',
+
+    # For a shared library build, results in "libv8-<(soname_version).so".
+    'soname_version%': '',
   },
   'target_defaults': {
     'conditions': [
       ['v8_enable_debugger_support==1', {
         'defines': ['ENABLE_DEBUGGER_SUPPORT',],
       }],
       ['v8_enable_disassembler==1', {
         'defines': ['ENABLE_DISASSEMBLER',],
       }],
       ['v8_enable_gdbjit==1', {
@@ skipping 204 matching lines @@
                 # some test cases can cause stack overflow.
                 # 'StackReserveSize': '297152',
               },
             },
           }],
         ],
       },
     },
   },
 }