Avoid specifying DART_SHARED_LIB in the static library GN targets

runtime/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.
 
 # TODO(zra): These build arguments should likely be moved to a gni file that is
 # included in BUILD.gn files that care about the values of the flags. For now,
 # since the GN build only happens as part of a Mojo build there is no need for
 # the indirection.
 declare_args() {
   # Instead of using is_debug, we introduce a different flag for specifying a
@@ skipping 153 matching lines @@
     "include/dart_mirrors_api.h",
     "include/dart_native_api.h",
     "include/dart_tools_api.h",
     "vm/dart_api_impl.cc",
     "vm/debugger_api_impl.cc",
     "vm/mirrors_api_impl.cc",
     "vm/native_api_impl.cc",
     "vm/version.h",
     "$target_gen_dir/version.cc",
   ]
-  defines = [
-    # Using DART_SHARED_LIB to export the Dart API entries.
-    "DART_SHARED_LIB",
-  ]
 }
 
 
 static_library("libdart_precompiled_runtime") {
   configs += [":dart_config_no_precompiler"]
   deps = [
     "vm:libdart_lib_precompiled_runtime",
     "vm:libdart_vm_precompiled_runtime",
     "third_party/double-conversion/src:libdouble_conversion",
     ":generate_version_cc_file",
   ]
   include_dirs = [
     ".",
   ]
   public_configs = [":dart_public_config"]
   sources = [
     "include/dart_api.h",
     "include/dart_mirrors_api.h",
     "include/dart_native_api.h",
     "include/dart_tools_api.h",
     "vm/dart_api_impl.cc",
     "vm/debugger_api_impl.cc",
     "vm/mirrors_api_impl.cc",
     "vm/native_api_impl.cc",
     "vm/version.h",
     "$target_gen_dir/version.cc",
   ]
   defines = [
-    # Using DART_SHARED_LIB to export the Dart API entries.
-    "DART_SHARED_LIB",
     "DART_PRECOMPILED_RUNTIME",
   ]
 }
 
 
 action("generate_version_cc_file") {
   deps = [
     ":libdart_dependency_helper",
   ]
   inputs = [
@@ skipping 21 matching lines @@
     "vm:libdart_lib_nosnapshot",
     "vm:libdart_lib",
     "vm:libdart_vm",
     "vm:libdart_platform",
     "third_party/double-conversion/src:libdouble_conversion",
   ]
   sources = [
     "vm/libdart_dependency_helper.cc",
   ]
 }