lavf/utils.c: Avoid a null pointer dereference on oom after duration_error allocation.
Suggest recompilation with openssl or gnutls if the https protocol is not found.

Fixes ticket #2765.
Merge remote-tracking branch 'cehoyos/master'

* cehoyos/master:
  Suggest recompilation with openssl or gnutls if the https protocol is not found.
  lavf/utils.c: Avoid a null pointer dereference on oom after duration_error allocation.

Merged-by: Michael Niedermayer <michaelni@gmx.at>