Remove non cancellable sigsuspend definition

There is no current internal usage for non cancellable sigsuspend calls.

Checked on x86_64-linux-gnu, x86_64-linux-gnu-x32, and i686-linux-gnu.

	* sysdeps/generic/not-cancel.h (sigsuspend_not_cancel): remove
	macro.
	* sysdeps/mach/hurd/sigsuspend.c (sigsuspend_not_cancel): remove
	alias.
	* sysdeps/unix/sysv/linux/not-cancel.h (sigsuspend_not_cancel):
	likewise.