Hide internal __ioctl function [BZ #18822]

Hide internal __ioctl function [BZ #18822]

Hide internal __ioctl function to allow direct access within libc.so and
libc.a without using GOT nor PLT.

__GI___ioctl is defined when sysdeps/unix/syscalls.list is used to
generate ioctl.  Otherwise libc_hidden_def is needed explicitly.

	[BZ #18822]
	* include/sys/ioctl.h (__ioctl): Add libc_hidden_proto.
	* misc/ioctl.c (__ioctl): Add libc_hidden_def.
	* sysdeps/mach/hurd/ioctl.c (__ioctl): Likewise.
	* sysdeps/unix/sysv/linux/aarch64/ioctl.S (__ioctl): Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/n64/ioctl.S (__ioctl):
	Likewise.
	* sysdeps/unix/sysv/linux/powerpc/ioctl.c (__ioctl): Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx/ioctl.S (__ioctl): Likewise.