This needs to be a concatenation of {nonxs,dynamic,static}_ext, as
shown by Config/Extensions.t.

Signed-off-by: Marcel Denia <naoir@gmx.net>

This replaces the previously used collection of configuration files for every single
architecture in conjunction with hacky overrides, which became an increasing burden to maintain.

Fixes a number of outstanding bugs and oddities, with the most important one being the
previously wrong signal order(as shown by ext/POSIX/t/sigaction.t).

See files/perlconfig.pl's POD and files/README.config for details.

Signed-off-by: Marcel Denia <naoir@gmx.net>