Get rid of yyrhs and yyprhs in yacc.c.

Get rid of yyrhs and yyprhs in yacc.c.

They were used to get the symbol types, given a rule number,  when
displaying the top of the stack before a reduction.  But the symbol type
is available from the state stack.  This has two be benefits: two tables
less in the parser (making it smaller), and a more consistent use of the
three stacks which will help to fuse them.

	* data/yacc.c (yyprhs, yyrhs): Remove.
	(YY_REDUCE_PRINT): Pass yyssp to yy_reduce_print.
	(yy_reduce_print): Take yyssp as argument.
	Use it, together with yystos, to get the symbol type.
	* tests/regression.at (Web2c Report): Remove these tables from the
	expected output.