[build] Disable gcc warnings for unittests

This is a workaround to silence gcc failures stemming from googletest
headers.

Bug: chromium:1307180
Change-Id: Ia6eb08f170f65c2fde6e4c287f9781d9df559b35
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3738220Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81548}

test/unittests/BUILD.gn

@@ -22,6 +22,15 @@ if (is_fuchsia) {
   }
 }
 
+config("gcc_warnings_not_errors") {
+  if (!is_clang && !is_win) {
+    cflags = [
+      # Turn off warning as errors due to false positives in googletest.
+      "-Wno-error",
+    ]
+  }
+}
+
 v8_executable("v8_heap_base_unittests") {
   testonly = true
 
@@ -50,6 +59,7 @@ v8_source_set("v8_heap_base_unittests_sources") {
   configs = [
     "../..:external_config",
     "../..:internal_config_base",
+    ":gcc_warnings_not_errors",
   ]
 
   deps = [
@@ -150,6 +160,7 @@ v8_source_set("cppgc_unittests_sources") {
     "../..:external_config",
     "../..:internal_config_base",
     "../..:cppgc_base_config",
+    ":gcc_warnings_not_errors",
   ]
 
   deps = [
@@ -619,6 +630,7 @@ v8_source_set("unittests_sources") {
     "../..:cppgc_base_config",
     "../..:external_config",
     "../..:internal_config_base",
+    ":gcc_warnings_not_errors",
   ]
 
   deps = [