freebsd stable - Sep 2016 - make universe fails with MAKEOBJDIRPREFIX [cross builds part: sh: ./make_keys: Exec format error for init_keytry.h]

Quoting:
> --- lib/ncurses/ncurses__L ---
> ./make_keys keys.list > init_keytry.h
. . .
> --- lib/ncurses/ncurses__L ---
> sh: ./make_keys: Exec format error
> *** [init_keytry.h] Error code 126

Since the reworking of the build handling in recent (many) months "sh:
./make_keys: Exec format error" is a long standing problem for buildworld
for cross builds. The native part of the build execution is trying to execute
the cross-build target's make_keys (that was likely left from a prior
cross-build and now doing incremental-build activity). lib/ncurses/ncurses__L is
not the only place that this can happen. There is past list exchanges for this
issue with other examples.

I rebuild after cleanworld when this happens in order to force a full rebuild
instead of an incremental one --but I only build one cross build target at a
time, not universe. I've never had such an after-cleanworld rebuild fail:
only some later incremental builds.

Luckily in my experience so far most incremental builds do not go back through
those areas (such as lib/ncurses/ncurses__L ) and so do not try to execute
make_keys (stated in terms of this example). So the incremental builds for me
are usually effective --but sometimes lib/ncurses/ncurses__L is rebuilt.

It has been a fairly long time since my 11.0 related activities (tracking
stable/11 now) have run into this but likely lib/ncurses/ncurses__L (and the
like) simply have not rebuilt in my cross builds. I've no head (CURRENT)
activities going on at this point.

==Mark Millard
markmi at dsl-only.net