Revert "deps: downgrade openssl to v1.0.0f"

This commit undoes the downgrade from OpenSSL v1.0.1e to v1.0.0f,
effectively upgrading OpenSSL to v1.0.1e again. The reason for the
downgrade was to work around compatibility issues with certain TLS
servers in the stable branch. See the commit log of 4fdb8acd and the
linked issue for details. We're going to revisit that in the master
branch.

This reverts commit 4fdb8acd.