that want a y.tab.h file. This want must be specified by putting y.tab.h
in SRCS (and defaulting to or putting -d in YFLAGS). This only works if
there is only one yacc parser, of course. One improvement: copy y.tab.c
to foo.c instead of renaming it, so that `#line...y.tab.c' statements in
it refer to an existing file.
Regress to not generating explicit rules for .l and .y sources containing
slashes. This case is unusual and hard to handle properly.
Don't generate an unused dependency when -d is not in YFLAGS.
cf1b9c0a35