One of our toolchains does not expose |errno| in the global namespace.
BUG=none
Review-Url: https://codereview.webrtc.org/2926273002
Cr-Commit-Position: refs/heads/master@{#18506}
They provide parsing of numbers from char* and std::string into any of
the fundamental integer types. Values are returned
in an rtc::Optional, which is left empty if parsing was unsuccessful.
BUG=webrtc:5806
Review-Url: https://codereview.webrtc.org/2696003004
Cr-Commit-Position: refs/heads/master@{#17557}
