Get numbered job history line from job summary file

Inputs:  Parm1 = Job Instance UJP pathname
         Parm3 = History number to retrieve

Output:  Parm2 = Retrieved History line
         Parm2 = (empty) (indicates no such history line)

Returns: Value passed in Parm3 (or -1 if no matching line)

This function retrieves the last line of the job history which has the passed Parm3 value in square brackets.  The line is returned in Parm2 and includes the inserted timestamp and the numeric value in square brackets.

When the function returns with an empty value in Parm2 there is no matching line in the history.