* hurd/hurd/threadvar.h: Include <features.h> for __THROW macro.

* hurd/hurd/threadvar.h: Include <features.h> for __THROW macro.

	* Versions.def (libc): Add GLIBC_2.2.6.
	* hurd/Versions (libc: GLIBC_2.2.6): Add __errno_location.
	* sysdeps/mach/hurd/errnos.awk: In generated macro, use
	__errno_location instead of __hurd_errno_location, and don't inline it.
	* sysdeps/mach/hurd/bits/errno.h: Regenerated.
	* hurd/errno.c: New file.
	* hurd/Makefile (routines): Add errno.