Cross-compiling MPIR 2.6.0 from Debian to MinGW-64

[Jean-Pierre Flori]

Dear all,

I had some troubles cross-compiling MPIR from Debian for MinGW-64 (using the debian provided mingw packages):
* most if not all (.asm, not sure for the others) files in mpn/x86_64w and surely sudirs have DOS file endings and make the compilation fail, running dos2unix solves the issue;
* when configuring MPIR to be cross-compiled, YASM also gets configured to be cross-compiled and so cannot be run on Linux, the solution being to reconfigure YASM after configuring MPIR in the top level directory not to use --host=x86_64-w64-mingw32 (or whatever version of MinGW[-64] you want to use).
After applying these two fixes, MPIR seems to compile fine (the static lib at least).
Please note I've not actually tested the produced library is functional as I don't usually have a Windows box at hand.

Best,
JP