* configure.in (libc_cv_gnu89_inline): Test for -fgnu89-inline.
* config.make.in (gnu89-inline-CFLAGS): New variable.
* Makeconfig (CFLAGS): Use $(gnu89-inline-CFLAGS) together with
-std=gnu99.
* misc/sys/cdefs.h (__extern_inline, __extern_always_inline): Define.
* argp/argp.h: Use it.
* bits/mathinline.h: Likewise.
* bits/sigset.h: Likewise.
* bits/string.h: Likewise.
* ctype/ctype.h: Likewise.
* hurd/hurd.h: Likewise.
* hurd/hurd/fd.h: Likewise.
* hurd/hurd/port.h: Likewise.
* hurd/hurd/signal.h: Likewise.
* hurd/hurd/threadvar.h: Likewise.
* hurd/hurd/userlink.h: Likewise.
* io/sys/stat.h: Likewise.
* libio/bits/stdio.h: Likewise.
* libio/bits/stdio2.h: Likewise.
* mach/lock-intern.h: Likewise.
* mach/mach/mig_support.h: Likewise.
* math/bits/cmathcalls.h: Likewise.
* posix/bits/unistd.h: Likewise.
* socket/bits/socket2.h: Likewise.
* stdlib/bits/stdlib.h: Likewise.
* stdlib/stdlib.h: Likewise.
* string/argz.h: Likewise.
* string/bits/string2.h: Likewise.
* string/bits/string3.h: Likewise.
* sysdeps/alpha/fpu/bits/mathinline.h: Likewise.
* sysdeps/generic/inttypes.h: Likewise.
* sysdeps/generic/machine-lock.h: Likewise.
* sysdeps/generic/machine-sp.h: Likewise.
* sysdeps/i386/fpu/bits/mathinline.h: Likewise.
* sysdeps/i386/i486/bits/string.h: Likewise.
* sysdeps/ia64/fpu/bits/mathinline.h: Likewise.
* sysdeps/mach/alpha/machine-lock.h: Likewise.
* sysdeps/mach/alpha/machine-sp.h: Likewise.
* sysdeps/mach/i386/machine-lock.h: Likewise.
* sysdeps/mach/powerpc/machine-lock.h: Likewise.
* sysdeps/mach/powerpc/machine-sp.h: Likewise.
* sysdeps/powerpc/fpu/bits/mathinline.h: Likewise.
* sysdeps/s390/bits/string.h: Likewise.
* sysdeps/s390/fpu/bits/mathinline.h: Likewise.
* sysdeps/sparc/fpu/bits/mathinline.h: Likewise.
* sysdeps/unix/bsd/bsd4.4/bits/socket.h: Likewise.
* sysdeps/unix/sysv/linux/bits/sigset.h: Likewise.
* sysdeps/unix/sysv/linux/bits/socket.h: Likewise.
* sysdeps/unix/sysv/linux/sys/sysmacros.h: Likewise.
* sysdeps/x86_64/fpu/bits/mathinline.h: Likewise.
* wcsmbs/bits/wchar2.h: Likewise.
* wcsmbs/wchar.h: Likewise.
* stdlib/gmp.h: Likewise. Include <features.h> to get
__extern_inline definition.
* locale/programs/ld-ctype.c (find_translit): Return NULL if ctype is
NULL.