options->app_type was set to mysql_sysvar_t* pointer,
later changed to sys_var* pointer, and even later dereferenced as
sys_var*. But for PLUGIN_VAR_NOSYSVAR variables the pointer wasn't
changed to sys_var*, so mysql_sysvar_t* pointer was dereferenced
(and updated!) as if it was sys_var*.

This caused maria.maria-gis-recovery test failure on x86 (fulltest2).