jent_read_entropy_safe() may return with dangling pointer in *ec.

[jc2a]

On a failure of jent_read_entropy() where the entropy collector will be reallocated, jent_entropy_collector_free() is used to release ec, but ec is not set to NULL. If a failure occurs in the following call to jent_entropy_collector_ex() then the function will return with a dangling pointer remaining in ec. Set ec to NULL after freeing to prevent this.

[joshuaehill]

I suspect that this is the reason for the observed core dumps in #88.

[smuellerDD]

Applied, thanks.