kernel build w/o DDB broken after c21bc6f

From: Michael Butler <imb_at_protected-networks.net>
Date: Fri, 22 Mar 2024 13:00:53 UTC
When a kernel is built without KDB and DDB, it fails with:

--- kernel.full ---
linking kernel.full
ld: error: undefined symbol: db_ctf_lookup_typename
 >>> referenced by kern_ctf.c:329 (/usr/src/sys/kern/kern_ctf.c:329)
 >>>               link_elf_obj.o:(link_elf_ctf_lookup_typename)
 >>> referenced by kern_ctf.c:329 (/usr/src/sys/kern/kern_ctf.c:329)
 >>>               link_elf.o:(link_elf_ctf_lookup_typename)
*** [kernel.full] Error code 1