use while (true) in do loops with continue

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/ast/arith_decl_plugin.cpp

@@ -984,7 +984,8 @@ bool arith_util::is_extended_numeral(expr* term, rational& r) const {
             return true;
         }
         return false;
-    } while (false);
+    } 
+    while (true);
     return false;
 }