fix character bom error

src/main/java/com/alibaba/druid/stat/JdbcSqlStat.java

@@ -394,7 +394,7 @@ public final class JdbcSqlStat implements JdbcSqlStatMBean {
             long current = executeSpanNanoMax.get();
             if (current < nanoSpan) {
                 if (executeSpanNanoMax.compareAndSet(current, nanoSpan)) {
-                    // �航�銝滚�蝖殷�雿�糓蝏嘥之憭𡁏㺭���銝钅�隡𡁏迤蝖殷��扯��Ｗ�銝?稲�?
+                	// 可能不准确，但是绝大多数情况下都会正确，性能换取一致性
                     executeNanoSpanMaxOccurTime = System.currentTimeMillis();
 
                     break;