crypto: Fix bug with takover of EC resource type

enif_open_resource_type() must be called even during repeated loading
of same library. Otherwise the resource type will be deallocated
when the old module instance is purged.
crypto: Fix some compiler warnings
crypto: Refactor remove resource for EC_KEY

The resource was not needed as it was never kept between external
crypto calls.
crypto: Supress some false positives from valgrind
Prepare release
Merge branch 'sverk/crypto-remove-ec-resource' into maint

* sverk/crypto-remove-ec-resource:
  crypto: Supress some false positives from valgrind
  crypto: Refactor remove resource for EC_KEY
  crypto: Fix some compiler warnings