GN: Use special toolchain for nacl64.exe, force is_component_build off

components/nacl/broker/BUILD.gn

Index: components/nacl/broker/BUILD.gn
diff --git a/components/nacl/broker/BUILD.gn b/components/nacl/broker/BUILD.gn
index 390f239bd3b7343bdbdcf57c28cee48cd09d8e62..aa8e3cb3fbe5f0b5feac034b23d5868b4389e013 100644
--- a/components/nacl/broker/BUILD.gn
+++ b/components/nacl/broker/BUILD.gn
@@ -58,9 +58,9 @@ if (current_cpu == "x86") {
     # NOTE: This must match what //build/config/BUILDCONFIG.gn uses
     # as default toolchain for the corresponding x64 build.
     if (is_clang) {
-      x64_toolchain = "//build/toolchain/win:clang_x64"
+      x64_toolchain = "//build/toolchain/win:clang_nacl_win64"
     } else {
-      x64_toolchain = "//build/toolchain/win:x64"
+      x64_toolchain = "//build/toolchain/win:nacl_win64"
     }
     nacl64_label = ":nacl64($x64_toolchain)"
     nacl64_out_dir = get_label_info(nacl64_label, "root_out_dir")
@@ -82,8 +82,13 @@ if (current_cpu == "x86") {
     # //build/config/compiler:optimize{,_max} adds this for official builds
     # only, as it only reduces binary size and is not necessary for
     # correctness.  But for nacl64.exe, it makes more than a six-fold
-    # difference in the binary size, so always use it.
-    ldflags = [ "/OPT:REF" ]
+    # difference in the binary size, so always use it in release builds.
+    # Note that using this flag disables incremental linking.  In debug
+    # builds, incremental rebuild time is usually of more concern than
+    # binary size, so incremental linking is preferable to size reduction.
+    if (!is_debug) {
+      ldflags = [ "/OPT:REF" ]
+    }
 
     sources = [
       "//chrome/nacl/nacl_exe_win_64.cc",