win: Remove "Compiler:" line from about:version; add "Linker:" line instead.

Shipping Chrome/Wins are now always built with clang, so the Compiler:
line is no longer needed. This part reverts
https://codereview.chromium.org/1404063002 (and some follow-ups).

We do want to switch the linker eventually, so add a "Linker:" line instead.

Bug: 82385,530785,792131
Change-Id: I0ecee267e468e04ee10590e1396df8c49110e595
Reviewed-on: https://chromium-review.googlesource.com/952486
Reviewed-by: Bernhard Bauer <bauerb@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#541448}
5 files changed