Changed Makefile.inc handling.

It seems more appropriate to trigger the inclusion of Makefile.inc via $TARGET (instead of $SRCDIR). This is btw. more consistent with extzp.s inclusion which is triggered via $TARGET too.
Check out install of MinGW cross devel packages.
Maybe better when avoiding transition packages?
Just playing to maybe understand more...
The last one worked - why? What about this...
Fixed typo.
Check what we have.
Moving on...
One more...
Okay, binutils-mingw-w64-i686 seems to have to be listed explicitly.
Removed -std=c89.

Using `struct stat` and `%m` surely doesn't qualify for ISO C90.