Move supportedgroup ext-block fields out of NO_EC

Now that we are moving to support named FFDH groups, these fields are not
ec-specific, so we need them to always be available.

This fixes the no-ec --strict-warnings build, since gcc
5.4.0-6ubuntu1~16.04.4 appears to always try to compile the static inline
functions from ssl_locl.h, even when they are not used in the current
compilation unit.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4518)