Minimal required changes to make it work for mariadb 10.2 (#857)

Always include mysql_version.h

Signed-off-by: Scott M. Likens <[email protected]>

Author: scottmlikens

ext/mysql2/mysql2_ext.h

@@ -14,11 +14,13 @@ void Init_mysql2(void);
 #include <mysql_com.h>
 #include <errmsg.h>
 #include <mysqld_error.h>
+#include <mysql_version.h>
 #else
 #include <mysql/mysql.h>
 #include <mysql/mysql_com.h>
 #include <mysql/errmsg.h>
 #include <mysql/mysqld_error.h>
+#include <mysql/mysql_version.h>
 #endif
 
 #ifdef HAVE_RUBY_ENCODING_H