You have somehow managed to generate a Makefile written for dmake ... but then that Makefile gets processed by nmake, and nmake doesn't understand Makefiles that were written for dmake.

You have a perl that specifies that perl -V:cc is cl and that perl -V:make is nmake. If you wish to use a mingw compiler to build a DBD module for that perl then the first thing you must do is to install ExtUtils::FakeConfig. And the second thing you must do is to set PER5OPT=-MConfig_m set PERL5OPT=-MConfig_m (Thanks to hv for the correction.)
Next you check that perl -V:make reports dmake and that perl -V:cc reports gcc. (If that's not happening, then something is not right.)
Then you have a chance of success ... or we'll at least start seeing helpful error messages. I know this is something that can work.

I actually think that if you were to instead use your MS compiler && provide correct command line arguments to the perl Makefile.PL ... command, then you might achieve what you want. But I don't know if this is something that can work.

In my opinion, the simplest solution is to just install one of the later "portable" editions of Strawberry Perl, where both DBD::MySQL and DBD::MariaDB are already installed, and can be updated using the cpan command if an upgrade of those modules is needed.
This is also something that can work.

Cheers,
Rob