[test] Auto-detect gcov-coverage builds

Bug: chromium:645890
Change-Id: I782934939ab04f63bde8e2f3a7bfef2715fa5e93
Reviewed-on: https://chromium-review.googlesource.com/552127Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46282}

BUILD.gn

@@ -804,6 +804,7 @@ action("v8_dump_build_config") {
   outputs = [
     "$root_out_dir/v8_build_config.json",
   ]
+  is_gcov_coverage = v8_code_coverage && !is_clang
   args = [
     rebase_path("$root_out_dir/v8_build_config.json", root_build_dir),
     "current_cpu=\"$current_cpu\"",
@@ -812,6 +813,7 @@ action("v8_dump_build_config") {
     "is_cfi=$is_cfi",
     "is_component_build=$is_component_build",
     "is_debug=$is_debug",
+    "is_gcov_coverage=$is_gcov_coverage",
     "is_msan=$is_msan",
     "is_tsan=$is_tsan",
     "target_cpu=\"$target_cpu\"",

tools/run-tests.py

@@ -495,6 +495,7 @@ def ProcessOptions(options):
       options.arch = 'ia32'
     options.asan = build_config["is_asan"]
     options.dcheck_always_on = build_config["dcheck_always_on"]
+    options.gcov_coverage = build_config["is_gcov_coverage"]
     options.mode = 'debug' if build_config["is_debug"] else 'release'
     options.msan = build_config["is_msan"]
     options.no_i18n = not build_config["v8_enable_i18n_support"]