Detect whether cc (the linker) is gcc or clang.

Detect whether cc (the linker) is gcc or clang.

Use this information to drive which options are added to the `cc`
command line arguments.

As a drive-by, fix an english grammar mistake in a comment.

This is meant to be, in part, a more robust version of PR #17192.

Fix #17214.
The argument against your first point is that in both of these calls we just ignore that part of the result, so it can't be _that_ important to draw attention to. That implies to me that there is certainly a use case for not computing it.

TBH, I'm not sure if it is too much overhead or not - in any case, the invocation much more than the string searches.

As I said, I don't feel too strongly about it, r+ either way.