This code is much more sophisticated in that it doesn't rely
on argv[0], but rather asks the OS where our executable is.
We can then simply go two steps up since we count on running
in out/Whatever relative to the src dir. This is how Chromium
does it.
The aim here is to get rid of SetExecutablePath, which will
be the next CL.
Bug: webrtc:9792
Change-Id: I7da027b7391e759b1f612de12f27a244fe884c09
Reviewed-on: https://webrtc-review.googlesource.com/c/103121
Reviewed-by: Artem Titov <titovartem@webrtc.org>
Commit-Queue: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25017}
