Catch up to b3051d01e505c9c2dc00faab472a0d06fa6b0e65

evp_md --> hash_alg
Catch up to 91b580e4bec55118bf96ab3cdbe5a50839e75d0a

kex_derive_keys() changed prototype
xmalloc is dead
new_ccname must be a pointer type
misc.h before servconf.h
Same cleanup for kexgsss as kexgssc
add base64'd krb5 mech OID to KEX_GSS_GEX_SHA1_ID

So that it actually works at runtime.
Quite ugly; we really want the prefix matching back that was lost
in ea11119eee3c5e2429b1f5f8688b25b028fa991a.
Attempt to bring back prefix-matching for kex algs
NOTICE: this is not a stable branch

Forced commit to note that this branch is draft construction and
may be destructively rebased without notice.

Buyer beware...