Fixed some NULL checks in EAP memory

  * Add a NULL check after the first talloc call
  * Fix the check after allocating eap_ds->request

Furthermore, I guess the code in eap_ds_free could be simplified, the talloc library should be able to free the response and request automatically.
Merge pull request #864 from qnet-herwin/talloc_null_check_eap_mem

Fixed some NULL checks in EAP memory
Fix more types in realms.c
Add xlat "poke" to change config of running modules
module test framework works for multiple modules
Compiler warnings