Remove more clang warnings.

clang warns that the yyinput function generated by flex is never used.

lexor.lex

@@ -40,6 +40,8 @@
 # define YY_USER_INIT reset_lexor();
 # define yylval VLlval
 
+# define YY_NO_INPUT
+
 /*
  * Lexical location information is passed in the yylloc variable to th
  * parser. The file names, strings, are kept in a list so that I can

vhdlpp/lexor.lex

@@ -35,6 +35,8 @@
 # include  <iostream>
 # include  <set>
 
+# define YY_NO_INPUT
+
 # define YY_DECL int yylex(YYSTYPE*yylvalp, YYLTYPE*yyllocp, yyscan_t yyscanner)
 //class vhdlnum;
 //class vhdlreal;

vvp/lexor.lex

@@ -29,6 +29,8 @@
 # include  <cassert>
 # include  "ivl_alloc.h"
 
+# define YY_NO_INPUT
+
 static char* strdupnew(char const *str)
 {
       return str ? strcpy(new char [strlen(str)+1], str) : 0;