Remove include/bits/ipc.h.

Remove include/bits/ipc.h.

Ten conformtest failures arise from the internal header
include/bits/ipc.h failing to condition internal declarations, outside
the public namespace of headers including bits/ipc.h, on [!_ISOMAC].
As discussed in
<https://sourceware.org/ml/libc-alpha/2015-06/msg00653.html>, the
internal declarations that are actually relevant are in ipc_priv.h and
so include/bits/ipc.h should not be needed at all; this patch removes
it.  (Ten further conformtest failures for other headers including
bits/ipc.h remain because of other conformance issues in those
headers.)

Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch).

	* include/bits/ipc.h: Remove file.
	* conform/Makefile (test-xfail-XPG3/sys/msg.h/conform): Remove
	variable.
	(test-xfail-XPG3/sys/shm.h/conform): Likewise.
	(test-xfail-XPG4/sys/msg.h/conform): Likewise.
	(test-xfail-XPG4/sys/shm.h/conform): Likewise.
	(test-xfail-UNIX98/sys/msg.h/conform): Likewise.
	(test-xfail-UNIX98/sys/shm.h/conform): Likewise.
	(test-xfail-XOPEN2K/sys/msg.h/conform): Likewise.
	(test-xfail-XOPEN2K/sys/shm.h/conform): Likewise.
	(test-xfail-XOPEN2K8/sys/msg.h/conform): Likewise.
	(test-xfail-XOPEN2K8/sys/shm.h/conform): Likewise.