Don't use --gdb-index for Gold and LLVM linker

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 08e9a9ef988737dcc6eaedee39e7b0021f20df0b..8e3092b21220178480f2fc1d63bb8078999eb5ba 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -1657,7 +1657,11 @@ config("symbols") {
     # builds, currently get
     # "third_party/binutils/Linux_x64/Release/bin/ld.gold: warning:
     # /tmp/lto-llvm-0b5201.o: corrupt debug info in .debug_info"
+    # TODO(thakis): Figure out how to make this go for Linux ARM64 Debug,

[kjellander_chromium, 2017/04/04 09:06:19]

Are you OK with me assigning a TODO for you? I personally don't know how to fix
this so putting my name in there wouldn't make any sense.

+    # currently get:
+    # /usr/bin/aarch64-linux-gnu-ld: unrecognized option '--gdb-index'
     if (!is_mac && !is_ios && !is_nacl && target_cpu != "x86" &&
+        !(is_linux && target_cpu == "arm64" && is_debug) &&

[Nico, 2017/04/04 13:47:29]

This is because we don't use gold in this config, yeah? Should this be &&
!(use_gold || use_lld)?

[kjellander_chromium, 2017/04/04 14:35:35]

Something along those lines sounds like the proper fix (I guess I'll remove the
TODO in that case).
But both those variables are false for Linux ARM64 Debug, so that will trigger
the same error. Any other suggestion?

[Nico, 2017/04/04 14:50:06]

Oh, I guess I mean (use_gold || use_lld) without the ! (sorry, bools are hard).

[kjellander_chromium, 2017/04/04 14:59:36]

:)
That works much better.

         !allow_posix_link_time_opt && !is_official_build) {
       ldflags += [ "-Wl,--gdb-index" ]
     }