kex: enable more ECDSA hostkey algos
kex: enable more ECDSA hostkey algos

Signed-off-by: Jon Simons <44f878afe53efc66b76772bd845eb65944ed8232@jonsimons.org>
Reviewed-by: Andreas Schneider <5be00ddc76278cf6077f5047ca3384a88460c671@cryptomilk.org>
(cherry picked from commit 40d81bb7cafe528639cb201e893ba62db1e813bf)

mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/libssh,mwgoldsmith/libssh,mwgoldsmith/ssh,mwgoldsmith/ssh,mwgoldsmith/libssh