est_server_http.c build issue

[rtmst3k]

When libcoap is enabled in the build of libest, the build breaks in est_server_http.c at line 1624 -- apparently the definition of coap_endpoint_t is incomplete so the dereference fails

[rtmst3k]

The above build failure could have been because I didn't apply the libcoap patch -- I'm using libcoap 4.2.1 and the patch file doesn't seem to work with this version of libcoap