Remove legacy configuration knobs from libio.

This patch eliminates the "compatibility defines"
_IO_UNIFIED_JUMPTABLES (always defined to 1, used in a number of #ifs
which are therefore always false), _STDIO_USES_IOSTREAM (unused),
__HAVE_COLUMN (unused), _IO_BE (replaced with __glibc_unlikely), and
yet another redundant definition of EOF.

Installed stripped libraries are unchanged by this patch.

	* libio/libio.h (_IO_UNIFIED_JUMPTABLES, _STDIO_USES_IOSTREAM)
	(__HAVE_COLUMN, _IO_BE): Don't define.
	(_IO_peekc_unlocked, _IO_getwc_unlocked, _IO_putwc_unlocked)
	(_IO_fwide_maybe_incompatible): Use __glibc_unlikely.
	* libio/libioP.h (EOF): Don't define.
	* libio/iofdopen.c, libio/iofopen.c, libio/iopopen.c
	* libio/iovdprintf.c, libio/oldiofdopen.c, libio/oldiofopen.c
	* libio/oldiopopen.c, debug/vdprintf_chk.c: Remove #if block
	testing _IO_UNIFIED_JUMPTABLES.