(#6326) add note explaining use of fseek over ungetc
(#6326) add note explaining use of fseek over ungetc

htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor,htcondor/htcondor