Add a new "pseudo" platform for POSIX

src/SConscript

 # Copyright 2008 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 48 matching lines @@
     'stub-cache-arm.cc', 'virtual-frame-arm.cc'
   ],
   'arch:ia32': [
     'assembler-ia32.cc', 'builtins-ia32.cc', 'codegen-ia32.cc',
     'cpu-ia32.cc', 'disasm-ia32.cc', 'debug-ia32.cc', 'frames-ia32.cc',
     'ic-ia32.cc', 'jump-target-ia32.cc', 'macro-assembler-ia32.cc',
     'regexp-macro-assembler-ia32.cc', 'register-allocator-ia32.cc',
     'stub-cache-ia32.cc', 'virtual-frame-ia32.cc'
   ],
   'simulator:arm': ['simulator-arm.cc'],
-  'os:freebsd': ['platform-freebsd.cc'],
-  'os:linux':   ['platform-linux.cc'],
-  'os:android': ['platform-linux.cc'],
-  'os:macos':   ['platform-macos.cc'],
+  'os:freebsd': ['platform-freebsd.cc', 'platform-posix.cc'],
+  'os:linux':   ['platform-linux.cc', 'platform-posix.cc'],
+  'os:android': ['platform-linux.cc', 'platform-posix.cc'],
+  'os:macos':   ['platform-macos.cc', 'platform-posix.cc'],
   'os:nullos':  ['platform-nullos.cc'],
   'os:win32':   ['platform-win32.cc'],
   'mode:release': [],
   'mode:debug': [
     'objects-debug.cc', 'prettyprinter.cc', 'regexp-macro-assembler-tracer.cc'
   ]
 }
 
 
 D8_FILES = {
@@ skipping 72 matching lines @@
     snapshot_obj = context.ConfigureObject(env, snapshot_cc, CPPPATH=['.'])
     libraries_obj = context.ConfigureObject(env, libraries_empty_src, CPPPATH=['.'])
   else:
     snapshot_obj = empty_snapshot_obj
   library_objs = [non_snapshot_files, libraries_obj, snapshot_obj]
   return (library_objs, d8_objs, [mksnapshot])
 
 
 (library_objs, d8_objs, mksnapshot) = ConfigureObjectFiles()
 Return('library_objs d8_objs mksnapshot')