Style nit fix for #943

Author: sodabrew

ext/mysql2/client.c

@@ -1546,12 +1546,12 @@ void init_mysql2_client() {
   rb_const_set(cMysql2Client, rb_intern("SECURE_CONNECTION"), LONG2NUM(0));
 #endif
 
-#ifdef MYSQL_OPTION_MULTI_STATEMENTS_ON
+#ifdef HAVE_CONST_MYSQL_OPTION_MULTI_STATEMENTS_ON
   rb_const_set(cMysql2Client, rb_intern("OPTION_MULTI_STATEMENTS_ON"),
       LONG2NUM(MYSQL_OPTION_MULTI_STATEMENTS_ON));
 #endif
 
-#ifdef MYSQL_OPTION_MULTI_STATEMENTS_OFF
+#ifdef HAVE_CONST_MYSQL_OPTION_MULTI_STATEMENTS_OFF
   rb_const_set(cMysql2Client, rb_intern("OPTION_MULTI_STATEMENTS_OFF"),
       LONG2NUM(MYSQL_OPTION_MULTI_STATEMENTS_OFF));
 #endif

ext/mysql2/extconf.rb

@@ -111,6 +111,8 @@ def add_ssl_defines(header)
 have_const('SERVER_QUERY_NO_GOOD_INDEX_USED', mysql_h)
 have_const('SERVER_QUERY_NO_INDEX_USED', mysql_h)
 have_const('SERVER_QUERY_WAS_SLOW', mysql_h)
+have_const('MYSQL_OPTION_MULTI_STATEMENTS_ON', mysql_h)
+have_const('MYSQL_OPTION_MULTI_STATEMENTS_OFF', mysql_h)
 
 # my_bool is replaced by C99 bool in MySQL 8.0, but we want
 # to retain compatibility with the typedef in earlier MySQLs.