japanese/prn: Fix git clone and working on repo under Windows

Windows can support long file names, but these file names are not allowed:
CON, PRN, AUX, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8,
COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9

Source: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file

Pull Request: https://github.com/freebsd/freebsd-ports/pull/122