Configuration: rework how dependency making is handled

Configuration: rework how dependency making is handled

Previously, we had dependency making pretty much hard coded in the
build file templates, with a bit of an exception for Unix family
platforms, where we had different cases depending on what dependency
making program was found.

With the Embarcadero C++ builder, a separate scheme appeared, with a
different logic.

This change merges the two, and introduces two config target
attributes:

    makedepcmd          The program to use, where this is relevant.
                        This replaces the earlier configuration
                        attribute 'makedepprog'.
    makedep_scheme      This is a keyword that can be used by build
                        files templates to produce different sorts of
                        commands, but most importantly, to pass as
                        argument to util/add-depend.pl, which uses
                        this keyword as a "producer" for the
                        dependency lines.

If the config target doesn't define the 'makedep_scheme' attribute,
Configure tries to figure it out by looking for GCC compatible
compilers or for the 'makedepend' command.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/15006)