CLEANUP: servers: do not include openssl-compat

CLEANUP: servers: do not include openssl-compat

This is exactly the same as for listeners, servers only include
openssl-compat to provide the SSL_CTX type to use as two pointers to
contexts, and to detect if NPN, ALPN, and cipher suites are supported,
and save up to 5 pointers in the ssl_ctx struct if not supported. This
is pointless, as these ones have all been supported for about a decade,
and including this file comes with a long dependency chain that impacts
lots of other files. The ctx was made a void*.

Now the build time was significantly reduced, from 9.2 to 8.1 seconds,
thanks to opensslconf.h being included "only" 456 times instead of 2424
previously!

The total number of lines of code compiled was reduced by 15%.