TRQ-2411: print the header only once

Changes:
- added global variable print_header for indication "need print header"

Tests demonstrating how it behaves in fixed version
$ src/cmds/.libs/qstat 53 52 54
Job ID                    Name             User            Time Use S Queue
------------------------- ---------------- --------------- -------- - -----
53.host                     STDIN            user                  0 Q batch
qstat: Unknown Job Id Error 52.host
54.host                     STDIN            user                  0 Q batch

e.g. 52 is incorrect JobId