TestImportTableInUnknownSection was introduced in CL 110555 to
test PE executable with import table located in section other than
".idata". We used atmfd.dll for that purpose, but it seems
atmfd.dll is not present on some systems.

Use kernel32.dll instead. kernel32.dll import table is located in
".rdata" section, so it should do the job. And every Windows
system has kernel32.dll file.

Also make TestImportTableInUnknownSection run on windows-arm,
since windows-arm should also have kernel32.dll file.

Updates #27904

Change-Id: Ie005ee10e46ae0c06e83929d581e89f86c051eea
Reviewed-on: https://go-review.googlesource.com/c/151137
Run-TryBot: Alex Brainman <alex.brainman@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>