Install sys/<arch>/include/pc/*.h to /usr/include/machine/pc/.
PR: docs/29534
Install sys/netatm/*/*.h to /usr/include/netatm/*/.
Don't install compatibility symlinks for <machine/soundcard.h>
and <machine/joystick.h>. Three years is enough to be aware of
the change, and these weren't visible in the SHARED=symlinks
case.
Back out include/Makefile,v 1.160 that was a null change anyway
due to the bug in the path, and we now don't want to install
these headers because they would otherwise be invisible in the
SHARED=symlinks case.
Don't install IPFILTER headers. Userland utilities fetch them
directly, and they were not visible in the SHARED=symlinks case.
Resurrect SHARED=symlinks in Makefile.inc1.
PR: bin/28002
Prodded by: bde
MFC after: 2 weeks
9f1207d517