NaCl-side GN changes to enable NaCl in Linux x64 Chrome builds.

build/toolchain/nacl/BUILD.gn

 # Copyright (c) 2014 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//native_client/build/config/sysroot.gni")
 import("//native_client/build/toolchain/nacl_toolchain.gni")
 
 declare_args() {
   nacl_toolchain_dir = rebase_path("//native_client/toolchain", root_build_dir)
 }
@@ skipping 108 matching lines @@
   toolchain_package = "pnacl_newlib"
   toolchain_revision = pnacl_newlib_rev
   toolchain_cpu_arch = "x86"
   toolprefix = "${os_toolchain_dir}/${toolchain_package}/bin/i686-nacl-"
   is_clang = true
 
   cc = toolprefix + "clang"
   cxx = toolprefix + "clang++"
   ar = toolprefix + "ar"
   readelf = toolprefix + "readelf"
-  # Link with cc to avoid including any C++ libs.
-  ld = "${python_path} ${link_irt} --tls-edit=tls_edit --link-cmd=${cc} --readelf-cmd=${readelf}"
+  # Some IRT implementations (notably, Chromium's) contain C++ code,
+  # so we need to link w/ the C++ linker.
+  ld = "${python_path} ${link_irt} --tls-edit=tls_edit --link-cmd=${cxx} --readelf-cmd=${readelf}"
 
   # TODO(ncbray): depend on link script
   deps = [
     "//native_client/src/tools/tls_edit:tls_edit($host_toolchain)",
   ]
 }
 
 nacl_toolchain("irt_x64") {
   toolchain_package = "pnacl_newlib"
   toolchain_revision = pnacl_newlib_rev
   toolchain_cpu_arch = "x64"
   toolprefix = "${os_toolchain_dir}/${toolchain_package}/bin/x86_64-nacl-"
   is_clang = true
 
   cc = toolprefix + "clang"
   cxx = toolprefix + "clang++"
   ar = toolprefix + "ar"
   readelf = toolprefix + "readelf"
-  # Link with cc to avoid including any C++ libs.
-  ld = "${python_path} ${link_irt} --tls-edit=tls_edit --link-cmd=${cc} --readelf-cmd=${readelf}"
+  # Some IRT implementations (notably, Chromium's) contain C++ code,
+  # so we need to link w/ the C++ linker.
+  ld = "${python_path} ${link_irt} --tls-edit=tls_edit --link-cmd=${cxx} --readelf-cmd=${readelf}"
 
   # TODO(ncbray): depend on link script
   deps = [
     "//native_client/src/tools/tls_edit:tls_edit($host_toolchain)",
   ]
 }
 
 # Uses newlib to match the Chrome build.
 nacl_toolchain("irt_arm") {
   toolchain_package = "nacl_arm_newlib"
   toolchain_revision = nacl_arm_newlib_rev
   toolchain_cpu_arch = "arm"
   toolprefix = "${os_toolchain_dir}/${toolchain_package}/bin/arm-nacl-"
 
   cc = toolprefix + "gcc"
   cxx = toolprefix + "g++"
   ar = toolprefix + "ar"
   readelf = toolprefix + "readelf"
-  # Link with cc to avoid including any C++ libs.
-  ld = "${python_path} ${link_irt} --tls-edit=tls_edit --link-cmd=${cc} --readelf-cmd=${readelf}"
+  # Some IRT implementations (notably, Chromium's) contain C++ code,
+  # so we need to link w/ the C++ linker.
+  ld = "${python_path} ${link_irt} --tls-edit=tls_edit --link-cmd=${cxx} --readelf-cmd=${readelf}"
 
   # TODO(ncbray): depend on link script
   deps = [
     "//native_client/src/tools/tls_edit:tls_edit($host_toolchain)",
   ]
 }