Correct the request of debug builds

./config would translate -d into having the target get a 'debug-'
prefix, and then run './Configure LIST' to find out if such a
debugging target exists or not.

With the recent changes, the separate 'debug-foo' targets are
disappearing, and we're giving the normal targets debugging
capabilities instead.  Unfortunately, './config' wasn't changed to
match this new behavior.

This change introduces the arguments '--debug' and '--release' - the
latter just for orthogonality - to ./Configure, and ./config now
treats -d by adding '--debug' to the options for ./Configure.

Reviewed-by: Matt Caswell <matt@openssl.org>