tests: fix part of the sys/compat32 breakage

[kevans]

Summary

The first iteration attempted to flatten out ^/tests/sys/compat32, since
we'll never need to install more than one set of compat32 tests for any
given architecture -- the arch directory ends up being generally
redundant. Unfortunately, the way it was accomplished was incredibly
fragile and relied on an arch subdir providing sys/compat32/Kyuafile.

Fix it by restructuring to operate generally like the libc build; the
^/tests/sys/compat32 Makefile contains the necessary boilerplate to put
a Kyuafile in the right directory regardless of what tests we end up
including, the arch subdirectory provides a Makefile.inc with the bits
needed for building.

The existing compat32 tests remain disabled until a path forward is
solidified for dealing with the build issues.

[jrtc27]

I assume this has been tinderboxed, or, really, test built for aarch64 and one other architecture?

tests/sys/compat32/aarch64/Makefile.inc

2

Reason for moving the comment?

[kevans]

In D40224#915710, @jrtc27 wrote:

I assume this has been tinderboxed, or, really, test built for aarch64 and one other architecture?

Yes; amd64 in addition, since a proper sanity check on this one requires an installworld + verification of the resulting Kyuafile structure.

tests/sys/compat32/aarch64/Makefile.inc

2

Whoops, just sloppy; had moved it further down to ACFLAGS and split off -target armv7-unknown-freebsd$(OS_REVISION) into -m32 -march=armv7 on a separate line with the comment above it to note that it just won't work with GCC still, but then reverted that manually and managed to botch the comment placement. Will move it back.