The protocol selection code is now consolidated in a few consecutive
short functions in a single file and is table driven.  Protocol-specific
constraints that influence negotiation are moved into the flags
field of the method structure.  The same protocol version constraints
are now applied in all code paths.  It is now much easier to add
new protocol versions without reworking the protocol selection
logic.

In the presence of "holes" in the list of enabled client protocols
we no longer select client protocols below the hole based on a
subset of the constraints and then fail shortly after when it is
found that these don't meet the remaining constraints (suiteb, FIPS,
security level, ...).  Ideally, with the new min/max controls users
will be less likely to create "holes" in the first place.

Reviewed-by: Kurt Roeckx <kurt@openssl.org>