Really, there should be a way to make configurable by the admin
at runtime (say, a gettmpdir() function).

off_t to be visible in stdio.h even in strict ansi mode.  This is needed
for ftello()/fseeko() and it allows us to remove the horrible fpos_t hack.

Also make fsetpos() and fgetpos() use fseeko() and ftello() respectively
since fpos_t is actually a 64bit type.

All POSIX libc api now there (to P1003.1c/D10)
(more md stuff is needed for other libc/arch/*)
(setlogin is no longer a special syscall)
Add -pthread option to gcc (that makes it use -lc_r and -D_POSIX_THREADS).
Doc some re-entrant routines
Add libc_r to intro(3)
dig() uses some libc srcs and an extra -I was needed there.
Add more md stuff to libc_r.
Update includes for the pthreads api
Update libc_r TODO

ones in the glibc.  Some man pages changes from FreeBSD
(asprintf.c/vasprintf.c are not based on GNU or FreeBSD code).

it is not fully compliant

sys/errno.h can declare it as well.