numerous fixes to sysv ipc

some of these definitions were just plain wrong, others based on
outdated ancient "non-64" versions of the kernel interface.

as much as possible has now been moved out of bits/*

these changes break abi (the old abi for these functions was wrong),
but since they were not working anyway it can hardly matter.

src/ipc/msgctl.c

@@ -5,8 +5,8 @@
 int msgctl(int q, int cmd, struct msqid_ds *buf)
 {
 #ifdef SYS_msgctl
-	return syscall(SYS_msgctl, q, cmd, buf);
+	return syscall(SYS_msgctl, q, cmd | 0x100, buf);
 #else
-	return syscall(SYS_ipc, IPCOP_msgctl, q, cmd, buf);
+	return syscall(SYS_ipc, IPCOP_msgctl, q, cmd | 0x100, 0, buf, 0);
 #endif
 }