add <? (min) and >? (max) operators

expr.c

@@ -90,6 +90,7 @@ struct {char str[4]; int pr;} ops[] = {
     {"*", 13},{"/",13},{"%",13},
     {"+",12},{"-",12},
     {"<<",11},{">>>",11},{">>",11},
+    {"<?",10},{">?",10},
     {"<=>",9},
     {"<=",8},{">=",8},{"<",8},{">",8},
     {"==",7},{"!=",7},
@@ -104,6 +105,7 @@ enum op {
     op_mul,op_div,op_mod,
     op_plus,op_minus,
     op_lshift,op_urshift,op_rshift,
+    op_min,op_max,
     op_cmp,
     op_lteq,op_gteq,op_lt,op_gt,
     op_eq,op_neq,