NAME
    UnLoadSeg -- Unload a seglist previously loaded by loadseg()
SYNOPSIS
    success = UnLoadSeg( seglist )
    D0                     D1
    BOOL UnLoadSeg(BPTR)
FUNCTION
    Unload a seglist loaded by loadseg().  'seglist' may be zero.
    Overlaid segments will have all needed cleanup done, including
    closing files.
INPUTS
    seglist - BCPL pointer to a segment identifier
RESULTS
    success - returns 0 if a NULL seglist was passed or if it failed
              to close an overlay file.  NOTE: this function returned
              a random value before V36!
SEE ALSO
    loadseg(), internalloadseg(), internalunloadseg()