Need to call init_mem() to really initialize the MMIO range lookups.

This was working by accident because:
- the RB_HEADs were being initialized to zero as part of BSS
- the pthread_rwlock functions were implicitly initializing the lock object

Obtained from:	NetApp

usr.sbin/bhyve/bhyverun.c

@@ -728,6 +728,7 @@ main(int argc, char *argv[])
 		exit(1);
 	}
 
+	init_mem();
 	init_inout();
 	init_pci(ctx);
 	if (ioapic)