remove unused field rule_line from struct imp_rule in the backend

backendC/CleanCompilerSources/buildtree.c

@@ -371,7 +371,6 @@ NewImpRule (unsigned line_number,TypeAlts typeAlternative,NodeP rule_root)
 
 	impRule->rule_alts = NIL;
 	impRule->rule_root = rule_root;
-	impRule->rule_line = line_number;
 	impRule->rule_type = typeAlternative;
 	impRule->rule_next_changed_function = NULL;
 

backendC/CleanCompilerSources/codegen1.c

@@ -2133,7 +2133,6 @@ ImpRuleP create_simple_imp_rule (NodeP lhs_root,NodeP rhs_root,SymbDefP function
 	imp_rule->rule_alts = rule_alt;
 	imp_rule->rule_root = lhs_root;
 	imp_rule->rule_mark = 0;
-	imp_rule->rule_line = 0;
 	imp_rule->rule_type = NULL;
 
 	function_sdef->sdef_rule=imp_rule;

backendC/CleanCompilerSources/optimisations.c

@@ -825,7 +825,6 @@ static void copy_alts (RuleAltP old_alts,RuleAlts *next_p,Symbol new_symbol)
 void copy_imp_rule_nodes (ImpRuleP old_rule_p,ImpRuleP new_rule_p)
 {
 	copy_alts (old_rule_p->rule_alts,&new_rule_p->rule_alts,new_rule_p->rule_type->type_alt_lhs->type_node_symbol);
-	new_rule_p->rule_line = old_rule_p->rule_line;
 	new_rule_p->rule_root = new_rule_p->rule_alts->alt_lhs_root;
 	new_rule_p->rule_mark = old_rule_p->rule_mark & RULE_CAF_MASK;
 }

backendC/CleanCompilerSources/syntaxtr.t

@@ -538,7 +538,6 @@ STRUCT (imp_rule,ImpRule){
 	struct node *				rule_strict_call_node;
 	struct node *				rule_strict_call_node2;
 #endif
-	unsigned					rule_line;
 	unsigned					rule_mark;
 };