Add a new GN arg: force_local_build_id

By default only official builds have build-ids. Setting
force_local_build_id = true can be used to add build-ids to
local builds as well.

Bug: 870919
Change-Id: I007ffbfb0d6005e980b4dea5a394471396ad3d92
Reviewed-on: https://chromium-review.googlesource.com/1231374
Commit-Queue: Leonard Mosescu <mosescu@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592174}

build/config/compiler/BUILD.gn

@@ -135,6 +135,9 @@ declare_args() {
   # the space overhead is too great. We should use some mixture of profiles and
   # optimization settings to better tune the size increase.
   thin_lto_enable_optimizations = is_chromeos
+
+  # By default only the binaries in official builds get build IDs.
+  force_local_build_id = false
 }
 
 declare_args() {
@@ -334,7 +337,7 @@ config("compiler") {
       }
     }
 
-    if (is_official_build) {
+    if (is_official_build || force_local_build_id) {
       # Explicitly pass --build-id to ld. Compilers used to always pass this
       # implicitly but don't any more (in particular clang when built without
       # ENABLE_LINKER_BUILD_ID=ON). The crash infrastructure does need a build