std::stod() on Solaris does not currently handle hex strings.
This commit provides a workaround based on strtol() until proper
stod() support is available.

This was encountered while updating Node.js to V8 8.8. For more
details see the following comment:

https://github.com/nodejs/node/pull/36139#issuecomment-740131942

Change-Id: I16ed80a817f6d9105e7153b10824b1fee8520432
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2692746Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Michael Stanton <mvstanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73255}