Use gomacc for host compiler in simple chrome build

I switched to use gomacc injection for chromeos toolchain in below CL.
https://chromium-review.googlesource.com/c/chromium/src/+/1151040

But simple chrome build also uses host compiler that does not know GOMACC_PATH
envvar. This CL revived goma's power for such toolchain.

This CL should be landed after cros side fix.
https://chromium-review.googlesource.com/c/chromiumos/chromite/+/1168277

And above CL was rolled.
https://chromium-review.googlesource.com/1168416

Bug: 872536
Change-Id: I938de4aea6c39b633a31cf1668ac147a9c6d0807
Reviewed-on: https://chromium-review.googlesource.com/1168275Reviewed-by: Alexander Alekseev <alemate@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#582047}

build/toolchain/gcc_toolchain.gni

@@ -151,9 +151,11 @@ template("gcc_toolchain") {
     # toolchain args, use those values, otherwise default to the global one.
     # This works because the only reasonable override that toolchains might
     # supply for these values are to force-disable them.
-    # But if has_gomacc_path is set, we assumes that compiler wrapper find
-    # gomacc from GOMACC_PATH envvar.
-    if (toolchain_uses_goma && !has_gomacc_path) {
+    # But if has_gomacc_path is set in simple chrome build, we assumes that
+    # *chromeos* compiler wrapper find gomacc from GOMACC_PATH envvar.
+    # Note: In this case, we use gomacc for host toolchain compiling.
+    if (toolchain_uses_goma &&
+        (!has_gomacc_path || invoker_toolchain_args.current_os != "chromeos")) {
       goma_path = "$goma_dir/gomacc"
 
       # Use the static analysis script if static analysis is turned on