The verilog preprocessing language is sufficiently simple
that the parser may be implemented by hand on top of the
lexical analyzer.
In fact, ivlpp was already implemented in this way; relevant
[bison] parser files specified no grammar, and the parser
entry-point (yyparse) was simply an indirect use of the lexical
analyzer (yylex).
Therefore, parse.y has been removed, invocations of yyparse()
have been replaced by yylex(), references to bison generated
files have been removed, and Makefile.in has been updated
accordingly.
Signed-off-by: Michael Witten <mfwitten@mit.edu>