* reset af to 0 in flushroutes() and newroute()
* cleanup -DSMALL:
- `flush' and AF_APPLETALK is supported (the latter had partial support)
- AF_NS, AF_ISO, and AF_CCITT are not supported at all (rather than being
- partially unsupported).
Also allow compilation with -DSMALL to ommit support for
non-essential protocols (i.e. when built into a ramdisk).
Use a less hack-ish way to generate keywords.[ch] and just
check in the result (helps ../../distrib/utils/x_route).