net-misc/aria2: Attempt to correct crazy crypto-lib logic
Attempt to rework crypto-lib dependencies to correctly indicate
libraries needed for program operation. The new logic involves using
OpenSSL only with USE=ssl+!gnutls but using it both for TLS & MD.
In all other circumstances, GnuTLS is used for TLS (if USE=ssl),
and nettle/libgcrypt is used for MD. The latter is needed independently
of bittorrent support; it only affects additional libgmp dependency.
Closes: https://bugs.gentoo.org/688780
Signed-off-by: Michał Górny <mgorny@gentoo.org>