feat(mqtt): 1.12.27, 修改example/mqtt/conn，使用采用2次退避重连策略

Author: hevake

examples/mqtt/conn/conn.cpp

@@ -43,7 +43,9 @@ int main(int argc, char **argv)
     mqtt::Client::Config conf;
     conf.auto_reconnect_enable = true;
     //conf.auto_reconnect_wait_sec = 5;
-    conf.auto_reconnect_wait_sec_gen_func = [](int fail_count) { return 1 << fail_count; };
+    conf.auto_reconnect_wait_sec_gen_func = [](int fail_count) {
+        return 1 << std::min(fail_count, 4);
+    };
 #if 0
     conf.base.broker.domain = "cppmain.cpp";
     conf.base.broker.port = 1883;

version.mk

@@ -21,4 +21,4 @@
 # TBOX版本号
 TBOX_VERSION_MAJOR := 1
 TBOX_VERSION_MINOR := 12
-TBOX_VERSION_REVISION := 26
+TBOX_VERSION_REVISION := 27