Safer fix for Bug #18435 "5.0.19 libmysqlclient not ABI-compatible with 5.0.18"

This fixes the problem if someone is using struct MYSQL as part of another structure together with a shared
library

include/mysql.h

@@ -287,8 +287,10 @@ typedef struct st_mysql
     from mysql_stmt_close if close had to cancel result set of this object.
   */
   my_bool *unbuffered_fetch_owner;
+#if defined(EMBEDDED_LIBRARY) || defined(EMBEDDED_LIBRARY_COMPATIBLE) || MYSQL_VERSION_ID >= 50100
   /* needed for embedded server - no net buffer to store the 'info' */
   char *info_buffer;
+#endif
 } MYSQL;
 
 typedef struct st_mysql_res {

sql-common/client.c

@@ -1428,13 +1428,7 @@ mysql_init(MYSQL *mysql)
     mysql->free_me=1;
   }
   else
-  {
-#if defined(EMBEDDED_LIBRARY) || MYSQL_VERSION_ID >= 50100
     bzero((char*) (mysql), sizeof(*(mysql)));
-#else
-    bzero((char*) (mysql), offsetof(MYSQL, info_buffer));
-#endif
-  }
   mysql->options.connect_timeout= CONNECT_TIMEOUT;
   mysql->last_used_con= mysql->next_slave= mysql->master = mysql;
   mysql->charset=default_charset_info;