Use __SIZEOF_POINTER__ which the GNU Fortran compiler defines at least
on 64-bit MinGW. Assume default size 4 on MinGW if gfortran does not
define the size.
Use a combination of response files and the archiver to support long
object file lists that do not fit in the Windows command-line length
limit. This can work only with GCC >= 4 because the MinGW GCC 3.x
front-ends do not support response-file syntax.
This moves GNU compiler info on Windows into new-style modules
Platform/Windows-GNU-<lang>.cmake
using language-independent helper module
Platform/Windows-GNU.cmake
to define macros consolidating the information.