buildroot

package/libssh2: fix dependency on libgcrypt

Since 2f89476 (package/libgpg-error: bump to version 1.23), libssh2 has
inherited the dependency from libgcrypt (propagated from libgpg-error).

However, since libssh2 can use either openssl or libgcrypt as a backend,
the dependency should be relaxed when openssl is available.

But the test is broken and inverted: it will make libssh unavailable as
soon as openssl is enabled.

Fix this dependenc byt doing what other similar packages do: select
openssl if the other crypto backend (here libgcrypt) is not enabled.
This also allows us to drop the propagated dependency on the arch
condition.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Cc: Jörg Krause <joerg.krause@embedded.rocks>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Cc: Romain Naour <romain.naour@openwide.fr>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>