build: Remove build system support for gold plugin, except under ChromeOS.

build/config/compiler/compiler.gni

Index: build/config/compiler/compiler.gni
diff --git a/build/config/compiler/compiler.gni b/build/config/compiler/compiler.gni
index 46b048f3ec3149783816604c98cfb0baa0a39200..079eba4a7e8633ab8842881c24f0ae094d615eef 100644
--- a/build/config/compiler/compiler.gni
+++ b/build/config/compiler/compiler.gni
@@ -120,6 +120,14 @@ declare_args() {
 }
 
 declare_args() {
+  # Set to true to use lld, the LLVM linker. This flag may be used on Windows
+  # or Linux.
+  use_lld = (is_win && host_os != "win") ||
+            ((allow_posix_link_time_opt || is_cfi) && target_os == "linux" &&

[Nico, 2017/05/17 23:14:29]

Shouldn't is_cfi imply allow_posix_link_time_opt? CFI requires LTO, no?

[pcc1, 2017/05/17 23:22:37]

It could do, I think. I'll see if I can do that as a separate cleanup.

+             !is_chromeos && target_cpu == "x64")
+}
+
+declare_args() {
   # Whether to use the gold linker from binutils instead of lld or bfd.
   use_gold =
       !use_lld && !(is_chromecast && is_linux &&