Call probe_expr_width() for repeat expression.

The repeat expression is evaluated in a self determined context
(expression width == -1). It needs to call probe_expr_width() to
figure out the width needed by the expression before calling
elab_and_eval() to elaborate the expression.

elaborate.cc

@@ -3675,6 +3675,7 @@ NetProc* PRepeat::elaborate(Design*des, NetScope*scope) const
 {
       assert(scope);
 
+      probe_expr_width(des, scope, expr_);
       NetExpr*expr = elab_and_eval(des, scope, expr_, -1);
       if (expr == 0) {
 	    cerr << get_fileline() << ": Unable to elaborate"