Rethink the uplink / applink story

Adding uplink and applink to some builds was done by "magic", the
configuration for "mingw" only had a macro definition, the Configure
would react to its presence by adding the uplink source files to
cpuid_asm_src, and crypto/build.info inherited dance to get it
compiled, and Makefile.shared made sure applink.o would be
appropriately linked in.  That was a lot under the hood.

To replace this, we create a few template configurations in
Configurations/00-base-templates.conf, inherit one of them in the
"mingw" configuration, the rest is just about refering to the
$target{apps_aux_src} / $target{apps_obj} in the right places.

Reviewed-by: Andy Polyakov <appro@openssl.org>