%N bugno %F $MIR/src/subs/bug.c
%D Issue an error message, given a system error number.
%P pjt
%: error-handling
%B
FORTRAN call sequence:
        subroutine bugno(severity,errno)

        implicit none
        character severity*1
        integer errno

  Output the error message associated with a particular error number.

  Input:
    severity    Error severity. Can be one of 'i', 'w', 'e' or 'f'
                for "informational", "warning", "error", or "fatal"
    errno       host error number.                                      
