Windows: Produce a static version of the public libraries, always

When building shared libraries on Windows, we had a clash between
'libcrypto.lib' the static routine library and 'libcrypto.lib' the
import library.

We now change it so the static versions of our libraries get '_static'
appended to their names.  These will never get installed, but can
still be used for our internal purposes, such as internal tests.

When building non-shared, the renaming mechanism doesn't come into
play.  In that case, the static libraries 'libcrypto.lib' and
'libssl.lib' are installed, just as always.

Fixes #7492

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7496)