(hurd_preempt_signals, hurd_unpreempt_signals): Decls removed.
* hurd/hurd/sigpreempt.h: New file.
* hurd/preempt-sig.c: Rewritten with new interface.
* sysdeps/mach/hurd/jmp-unwind.c (_longjmp_unwind): Remove local signal
preempters being unwound past.
* db: New directory, 4.4 BSD db package incorporated from BSD db-1.85
release.
* sysdeps/unix/sysv/linux/sys/param.h: Several new macros for BSD
compatibility.
* sysdeps/generic/confname.h: Define all names as self-referential
macros so #ifdef works.
* hurd/preempt-sig.c (hurd_unpreempt_signals): Remove bogus asgnmt
of _hurd_signal_preempters[SIGNO].