DF-1244 fix compile-validation (mrsas module)
==============================================
Guest: DragonFly 6.5-DEVELOPMENT #0, gcc 8.3, KERNCONF=X86_64_GENERIC
Applied: fix.diff (bounds check on targetId before ld_ids[ids])

Build command: cd /usr/src/sys/dev/raid/mrsas && make KERNCONF=X86_64_GENERIC
Result: RC=0 (success, no errors, no warnings, -Werror)

Key compile line (mrsas.c — the patched file):
  cc -O2 -pipe -D_KERNEL -Wall ... -Werror -DKLD_MODULE -nostdinc ... -c /usr/src/sys/dev/raid/mrsas/mrsas.c
  (compiled cleanly)

Link line:
  cc -Wl,--build-id=sha1 -nostdlib -Wl,--hash-style=sysv -r -Wl,-d -o mrsas.ko mrsas.o mrsas_cam.o mrsas_ioctl.o mrsas_fp.o

Output artifact:
  /usr/obj/usr/src/sys/dev/raid/mrsas/mrsas.ko — 88328 bytes (ELF 64-bit LSB relocatable, x86-64)
  /usr/obj/usr/src/sys/dev/raid/mrsas/mrsas.o   — 57728 bytes

Conclusion: fix.diff compiles cleanly into the mrsas kernel module. No runtime test
possible (MegaRAID SAS controller absent from QEMU guest) — see VERDICT.md.