Use common bits/msq.h for more architectures.

sysdeps/unix/sysv/linux/bits/msq.h has padding after time fields in
struct msqid_ds unconditionally, and thus is only suitable for 32-bit
architectures (no 64-bit configurations use this file);
sysdeps/unix/sysv/linux/generic/bits/msq.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/msq.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.

Tested with build-many-glibcs.py.

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