Enable -Wunreachable-code for internal iOS builds.

With this, -Wunreachable-code is enabled on all platforms for
chromium_code (which is the default config for all GN targets).

Targets that explicitly opt out of chromium_code and into
no_chromium_code don't get the warning.

(libfuzzer builds also don't get the warning, that's issue 1063180).

Bug: 346399
Change-Id: I88ea45eddf55d4ba5170ff89367d6afcf27891a1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2128189
Commit-Queue: Nico Weber <thakis@chromium.org>
Auto-Submit: Nico Weber <thakis@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#754643}

build/config/compiler/BUILD.gn

@@ -1591,8 +1591,7 @@ config("chromium_code") {
 
     # TODO(thakis): Enable this more often, https://crbug.com/346399
     # use_libfuzzer: https://crbug.com/1063180
-    if (!is_nacl && !use_libfuzzer &&
-        !(is_ios && ios_app_bundle_id_prefix != "org.chromium")) {
+    if (!is_nacl && !use_libfuzzer) {
       cflags += [ "-Wunreachable-code" ]
     }