Fix cross-compilation of C# interface.
Fix cross-compilation of C# interface.

msteinbeck/tinyspline,msteinbeck/tinyspline,msteinbeck/tinyspline,msteinbeck/tinyspline,retuxx/tinyspline,msteinbeck/tinyspline,msteinbeck/tinyspline,retuxx/tinyspline,msteinbeck/tinyspline,retuxx/tinyspline,msteinbeck/tinyspline