NCL fixes to that were breaking windows 64-bit build through on MinGW g++ 4.2

Below is a zip file with the 3 files (nxsmultiformat.cpp nxsstring.cpp ncl/nxsstring.h) I had to change to make this version of g++ happy with phylobase. I was not able to do a full test as I don't have TeX on that machine. But the build seemed to work. all of the affected files are in pkg/src (or the ncl subdir of that directory).