cannot make pc0 from makefile

[utzoo!decvax!genradbo!linus!smk]

	From the 4.1bsd distribution, the makefile in
/usr/src/cmd/pc0 does not make pc0 correctly.  The make depend
is supposed to create a y.tab.c and y.tab.h using eyacc,
but eyacc does not make the y.tab.h.  The source to eyacc shows
it is incapable to do that.  I came across this while trying to
fix that old pc0 bug mentioned months earlier.  Has anyone
tried to fix the bug and succeeded?  If so, may I have the makefile
(or have I been stupid and done something incorrectly)?
	--steve