[TF] Improper clean target in a11

[jrh at zeppelin.n. (J. Howard)]

Along the lines of semi-broken configure stuff. 'make clean' doesn't
seem to work properly.

jrh@levee:temp/tf-50a11> gmake clean
gmake[1]: Entering directory `/usr/home/jrh/temp/tf-50a11/src'
cd ..; ./unixmake clean
./unixmake: not found
gmake[1]: *** [clean] Error 127
gmake[1]: Leaving directory `/usr/home/jrh/temp/tf-50a11/src'
gmake: *** [clean] Error 2

Seems unix/unix.mak is a little out of date with respect to its clean
target.


-- 
Josh Howard <jr...@ze...>