src/sys/dev/an/if_an_pccard.c rev 1.10 change requires to include
"card_if.h" but Makefile doesn't know about this file. Without this,
kernel build will fail at this driver.
This means that the kernel can be totally self contained now and is not
dependent on the last buildworld to update /usr/share/mk. This might
also make it easier to build 5.x kernels on 4.0 boxes etc, assuming
gensetdefs and config(8) are updated.
