Simplify Makefile.shared

Makefile.shared was designed to figure out static library names,
shared library names, library version compatibility, import library
names and the like on its own.  This was a design for pre-1.1.0
OpenSSL because the main Makefile didn't have all that knowledge.

With 1.1.0, the situation isn't the same, a lot more knowledge is
included in the main Makefile, and while Makefile.shared did things
right most of the time (there are some corner cases, such as the
choice of .sl or .so as DSO extension on some HPUX versions), there's
still an inherent fragility when one has to keep an eye on
Makefile.shared to make sure it produces what the main Makefile
produces.

This change simplifies Makefile.shared by removing all its
"intelligence" and have it depend entirely on the input from the main
Makefile instead.  That way, all the naming is driven from
configuration data.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3983)