* cygserver.h (struct header_t): Revert msglen to simple member.
	Drop accessor methods.
	* cygserver_ipc.h (struct proc): Drop enforced 4 byte struct packing.
	Remove members for 64<->32 bit IPC.  Revert to original member order.
	(ipc_set_proc_info): Remove 64<->32 handling.
	(conv_timespec32_to_timespec): Delete.
	(conv_timespec_to_timespec32): Delete.
	* pinfo.h (struct win_heap_info): Remove.
	* shm.cc (fixup_shms_after_fork): Revert parent initialization.
	* winlean.h: Remove _TYPE64_CLR and _TYPE64_SET macros.  Remove
	usage throughout code.
	* include/cygwin/ipc.h: Drop 64<->32 bit helper structures.
	* include/cygwin/msg.h: Ditto.  Drop enforced 4 byte struct packing.
	* include/cygwin/sem.h: Ditto.
	* include/cygwin/shm.h: Ditto.
	* include/cygwin/sysproto.h: Drop enforced 4 byte struct packing.