Make function bodies rely on the parameter variable declarations.

Previously, generating inlined function bodies was going to be
difficult, as there was no mapping between the body's declaration of
variables where parameter values were supposed to live and the
parameter variables that a caller would use in paramater setup.
Presumably this also have been a problem for actual codegen.

ast_to_hir.cpp

     */
    state->symbols->push_scope();
    foreach_iter(exec_list_iterator, iter, signature->parameters) {
-      ir_variable *const proto = ((ir_instruction *) iter.get())->as_variable();
+      ir_variable *const var = ((ir_instruction *) iter.get())->as_variable();
 
-      assert(proto != NULL);
-
-      ir_variable *const var = proto->clone();
-
-      signature->body.push_tail(var);
+      assert(var != NULL);
 
       /* The only way a parameter would "exist" is if two parameters have
        * the same name.

builtin_function.cpp

    for (i = 0; i < n_args; i++) {
       ir_variable *var = new ir_variable(type, arg_names[i]);
 
-      var = new ir_variable(type, arg_names[i]);
       var->mode = ir_var_in;
       sig->parameters.push_tail(var);
 
-      var = new ir_variable(type, arg_names[i]);
-      var->mode = ir_var_in;
-      sig->body.push_tail(var);
       declarations[i] = var;
    }
 

glsl_types.cpp

       var->mode = ir_var_in;
       signature->parameters.push_tail(var);
 
-      var = new ir_variable(parameter_type, names[i]);
-
-      var->mode = ir_var_in;
-      signature->body.push_tail(var);
-
       declarations[i] = var;
    }
 

ir_print_visitor.cpp

 void ir_print_visitor::visit(ir_label *ir)
 {
    printf("\n(label %s\n", ir->label);
+
    ir->signature->accept(this);
    printf(")");
 }
 
 void ir_print_visitor::visit(ir_function_signature *ir)
 {
+   printf("(paramaters\n");
+   foreach_iter(exec_list_iterator, iter, ir->parameters) {
+      ir_variable *const inst = (ir_variable *) iter.get();
+
+      inst->accept(this);
+      printf("\n");
+   }
+   printf(")\n");
+
    foreach_iter(exec_list_iterator, iter, ir->body) {
       ir_instruction *const inst = (ir_instruction *) iter.get();