cmd/link: ignore SEH marking on PE objects

Microsoft's linker looks at whether all input objects have an empty
section called @feat.00. If all of them do, then it enables SEH;
otherwise it doesn't enable that feature. So, since around the Windows
XP SP2 era, most tools that make PE objects just tack on that section,
so that it won't gimp Microsoft's linker logic. Go doesn't support SEH,
so in theory, none of this really matters to us. But actually, if the
linker tries to ingest an object with @feat.00 -- which are produced by
LLVM's resource compiler, for example -- it chokes because of the
IMAGE_SYM_ABSOLUTE section that it doesn't know how to deal with. Since
@feat.00 is just a marking anyway, skip IMAGE_SYM_ABSOLUTE sections that
are called @feat.00.

Change-Id: I1d7bfcf6001186c53e2c487c5ac251ca65efefee
Reviewed-on: https://go-review.googlesource.com/c/go/+/268239


Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Trust: Alex Brainman <alex.brainman@gmail.com>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>