Use common bits/sem.h for more architectures.

Use common bits/sem.h for more architectures.

sysdeps/unix/sysv/linux/bits/sem.h has padding after time fields in
struct semid_ds unconditionally, and thus is only suitable for 32-bit
architectures (no 64-bit configurations use this file);
sysdeps/unix/sysv/linux/generic/bits/sem.h is substantively the same,
except that the padding is conditioned on __WORDSIZE == 32, and so it
can be used for 64-bit architectures as well.

This patch adds the conditionals to
sysdeps/unix/sysv/linux/bits/sem.h.  The linux/generic/ version is
then no longer needed and so is removed, as are the alpha, ia64 and
s390 versions which are also no longer needed.  The other
architecture-specific versions have different padding or types and so
are still needed after this change.

This is essentially the same change for bits/sem.h as the bits/msq.h
patch.  However, the details of the padding variations for the
architectures that aren't changed are not all the same between
msqid_ds and semid_ds.

Tested with build-many-glibcs.py.

	* sysdeps/unix/sysv/linux/bits/sem.h: Include <bits/wordsize.h>.
	(struct semid_ds): Condition padding after time fields on
	[__WORDSIZE == 32].
	* sysdeps/unix/sysv/linux/alpha/bits/sem.h: Remove file.
	* sysdeps/unix/sysv/linux/generic/bits/sem.h: Likewise.
	* sysdeps/unix/sysv/linux/ia64/bits/sem.h: Likewise.
	* sysdeps/unix/sysv/linux/s390/bits/sem.h: Likewise.