Allow building for windows

CMakeLists.txt

argp/argp-ba.c

argp/argp-eexst.c

argp/argp-fmtstream.c

argp/argp-fmtstream.h

argp/argp-fs-xinl.c

argp/argp-help.c

argp/argp-parse.c

argp/argp-pin.c

argp/argp-pv.c

argp/argp-pvh.c

argp/argp.h

argp/getopt.c

argp/getopt.h

argp/getopt1.c

argp/getopt_init.c

argp/getopt_int.h

constantphase.cpp

crossW64.cmake

main.cpp