Moves BUILD.gn config from root to runtime.

runtime/bin/BUILD.gn

 # Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 
 declare_args() {
   dart_io_support = false
 }
 
 
@@ skipping 70 matching lines @@
 }
 
 
 builtin_impl_sources_gypi =
     exec_script("../../tools/gypi_to_gn.py",
                 [rebase_path("builtin_impl_sources.gypi")],
                 "scope",
                 ["builtin_impl_sources.gypi"])
 
 static_library("libdart_builtin") {
-  configs += ["../..:dart_config"]
+  configs += ["..:dart_config"]
   public_configs = [":libdart_builtin_config"]
   deps = [
     ":generate_builtin_cc_file",
     ":generate_io_cc_file",
     ":generate_io_patch_cc_file",
   ]
   include_dirs = [
     "..",
   ]
   set_sources_assignment_filter(["*_test.cc", "*_test.h"])
   sources = [
     "log_android.cc",
     "log_linux.cc",
     "log_macos.cc",
     "log_win.cc",
   ] + builtin_impl_sources_gypi.sources
 }
 
 
 static_library("libdart_withcore") {
-  configs += ["../..:dart_config"]
+  configs += ["..:dart_config"]
   deps = [
     "../vm:libdart_lib_withcore",
     "../vm:libdart_vm",
     "../vm:libdart_platform",
     "../third_party/jscre:libjscre",
     "../third_party/double-conversion/src:libdouble_conversion",
     "..:generate_version_cc_file",
   ]
 
   sources = [
@@ skipping 12 matching lines @@
     "..",
   ]
 
   defines = [
     "DART_SHARED_LIB",
   ]
 }
 
 
 executable("gen_snapshot") {
-  configs += ["../..:dart_config"]
+  configs += ["..:dart_config"]
   deps = [
     ":libdart_withcore",
     ":libdart_builtin",
   ]
 
   sources = [
     "gen_snapshot.cc",
     # Very limited native resolver provided.
     "builtin_gen_snapshot.cc",
     "builtin.cc",
     "builtin.h",
     # Include generated source files.
     "$target_gen_dir/builtin_gen.cc",
     "$target_gen_dir/io_gen.cc",
     "$target_gen_dir/io_patch_gen.cc",
   ]
 
   include_dirs = [
     "..",
   ]
 }
 
 
 static_library("libdart_embedder_noio") {
-  configs += ["../..:dart_config",]
+  configs += ["..:dart_config",]
   deps = [
     "..:libdart",
     "../vm:libdart_platform",
   ]
 }