Add the possibility to build with PGO when using Clang

chrome/test/data/nacl/BUILD.gn

 # Copyright 2015 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/features.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/toolchain.gni")
 import("//ppapi/native_client/nacl_test_data.gni")
 
 group("nacl") {
@@ skipping 584 matching lines @@
       # undefined references left.
       "-Wl,--no-undefined",
 
       # Silence the warning about the unused '-pthread' argument.
       # TODO(gn): Come up with a way to remove the -pthread flag instead.
       "-Qunused-arguments",
     ]
     defines = [ "NACL_LINUX=1" ]
     include_dirs = [ "../../../.." ]
 
+    # Do not use PGO, which requires a few symbols.
+    configs -= [ "//build/config/pgo:default_pgo_flags" ]

[Sébastien Marchand, 2016/11/17 17:31:15]

Again, I'll do the opposite, include it when you need it.

+
     # Do not use any sanitizers tools, which require a few symbols.
     configs -= [ "//build/config/sanitizers:default_sanitizer_flags" ]
     configs += [ ":nonsfi_libc_free_nexe_config" ]
   }
 
   copy("nonsfi_libc_free") {
     sources = [
       "${root_out_dir}/libc_free_${arch}.nexe",
 
       # TODO(ncbray) move into chrome/test/data/nacl when all tests are
       # converted.
       "//ppapi/native_client/tools/browser_tester/browserdata/nacltest.js",
       "nonsfi/irt_test.html",
       "nonsfi/libc_free.html",
       "nonsfi/libc_free.nmf",
     ]
     outputs = [
       "${root_build_dir}/nacl_test_data/libc-free/{{source_file_part}}",
     ]
     deps = [
       ":nonsfi_libc_free_nexe",
     ]
   }
 }