* Makefile.in (mingw-hdep.o, posix-hdep.o): New dependencies.
(ALLDEPFILES): Add mingw-hdep.c and posix-hdep.c.
* configure.ac: Add gdb_host_obs to CONFIG_OBS. Set gdb_host_obs
to posix-hdep.o by default.
* configure: Regenerated.
* configure.host: Document gdb_host_obs. Add an entry for
i[34567]86-*-mingw32*.
* mingw-hdep.c, posix-hdep.c: New files.
* utils.c (safe_strerror): Remove, moved to posix-hdep.o.