Move pthread flags out compiler config.

build/config/compiler/BUILD.gn

 # Copyright (c) 2013 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/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/config/sanitizers/sanitizers.gni")
@@ skipping 483 matching lines @@
 
   # Assign any flags set for the C compiler to asmflags so that they are sent
   # to the assembler. The Windows assembler takes different types of flags
   # so only do so for posix platforms.
   if (is_posix) {
     asmflags += cflags
     asmflags += cflags_c
   }
 }
 
+# This is separate from :compiler (and not even a sub-config there)
+# so that some targets can remove it from the list with:
+#   configs -= [ "//build/config/compiler:pthread" ]
+config("pthread") {
+  if (is_linux) {
+    cflags = [ "-pthread" ]
+    ldflags = [ "-pthread" ]
+  }
+}
+
 # This provides the basic options to select the target CPU and ABI.
 # It is factored out of "compiler" so that special cases can use this
 # without using everything that "compiler" brings in.  Options that
 # tweak code generation for a particular CPU do not belong here!
 # See "compiler_codegen", below.
 config("compiler_cpu_abi") {
   cflags = []
   ldflags = []
 
   if (is_posix && !(is_mac || is_ios)) {
@@ skipping 1120 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }