Change default DARWIN_SYSROOT
Add new arg to tidy_patches

.. FINAL, whether this is the complete patch-set or
are fixing some mid patch-set patch, if FINAL then
the 9999-re-configure-d.patch is re-made, otherwise
some information is displayed.
Fix non-MSYS compilation

My --root= hack caused relative install folders
for the .so files, so only do this hack on MSYS

Also added a test of using crosstool-ng based
darwin cross compilers.
Added option to build with gcc and/or clang:

--compiler-vendors=<gcc,clang>

.. you need the compilers for every system that you
build for unfortunately; but then again, having the
complete set of compilers for every system is quite
a good idea, and this project is used as a test-bed
for improving and adding Darwin / Clang / MinGW-w64
support to crosstool-ng here:

https://github.com/diorcety/crosstool-ng