In this version of OpenSSL, declarations aren't always strict

In this version of OpenSSL, declarations aren't always strict
prototypes, so I'm removing -Wstrict-prototypes and
-Wmissing-prototypes from my debugging target in favor of
-Wmissing-declarations.  That will make other issues more visible than
in the middle of a thousand warnings telling me there isn't a proper
prototype for this or that function pointer...