[builtins-pgo] Minor fixes in the profile reader

This CL also makes the PGO-related scripts executable.

Bug: v8:10470
Change-Id: Iedf81464ff591e641aae4f1f0aa37312875f2637
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3716482Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Auto-Submit: Igor Sheludko <ishell@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81305}

src/builtins/profile-data-reader.cc

@@ -62,6 +62,7 @@ EnsureInitProfileData() {
       CHECK(std::getline(line_stream, builtin_name, ','));
       CHECK(std::getline(line_stream, token, ','));
       char* end = nullptr;
+      errno = 0;
       uint32_t true_id = static_cast<uint32_t>(strtoul(token.c_str(), &end, 0));
       CHECK(errno == 0 && end != token.c_str());
       CHECK(std::getline(line_stream, token, ','));