Use icu_gyp_path variable to reference ICU gyp file

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 837 matching lines @@
             'V8_SHARED',
           ],
         }],
         ['v8_postmortem_support=="true"', {
           'sources': [
             '<(SHARED_INTERMEDIATE_DIR)/debug-support.cc',
           ]
         }],
         ['v8_enable_i18n_support==1', {
           'dependencies': [
-            '<(DEPTH)/third_party/icu/icu.gyp:icui18n',
-            '<(DEPTH)/third_party/icu/icu.gyp:icuuc',
+            '<(icu_gyp_path):icui18n',
+            '<(icu_gyp_path):icuuc',
           ]
         }, {  # v8_enable_i18n_support==0
           'sources!': [
             '../../src/i18n.cc',
             '../../src/i18n.h',
           ],
         }],
         ['OS=="win" and v8_enable_i18n_support==1', {
           'dependencies': [
-            '<(DEPTH)/third_party/icu/icu.gyp:icudata',
+            '<(icu_gyp_path):icudata',
           ],
         }],
       ],
     },
     {
       'target_name': 'js2c',
       'type': 'none',
       'conditions': [
         ['want_separate_host_toolset==1', {
           'toolsets': ['host'],
@@ skipping 160 matching lines @@
         }],
         ['v8_compress_startup_data=="bz2"', {
           'libraries': [
             '-lbz2',
           ]
         }],
       ],
     },
   ],
 }