fuchsia: Let linker know where to find libclang_rt.builtin.a

build/config/fuchsia/BUILD.gn

 # Copyright 2017 The Chromium 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("//build/config/fuchsia/config.gni")
 import("//build/config/sysroot.gni")
 
 assert(is_fuchsia)
 assert(is_posix)
 
 config("compiler") {
   defines = [ "SYSROOT_VERSION=$sysroot_version" ]
   cflags = []
   ldflags = []
   if (current_cpu == "arm64") {
     cflags += [ "--target=aarch64-fuchsia" ]
     ldflags += [ "--target=aarch64-fuchsia" ]
   } else if (current_cpu == "x64") {
     cflags += [ "--target=x86_64-fuchsia" ]
     ldflags += [ "--target=x86_64-fuchsia" ]
   } else {
     assert(false, "Unsupported architecture")
   }
   asmflags = cflags
 
+  # TODO(thakis): Once Fuchsia's libclang_rt.builtin no longer has upstream
+  # patches, we might want to make tools/clang/scripts/update.py build it
+  # and bundle it with the clang package instead of using the library from
+  # the SDK.

[scottmg, 2017/05/19 19:53:55]

Maybe link crbug.com/724204 here.

[Nico, 2017/05/19 19:54:56]

Done.

+  ldflags += [
+    "-resource-dir",
+    rebase_path(fuchsia_sdk, root_build_dir) + "/toolchain_libs/clang/5.0.0",
+  ]
+
   libs = [
     "mxio",
     "magenta",
     "unwind",
   ]
 }