show minimal backtrace if gdb is not installed

show minimal backtrace if gdb is not installed

- here is a sample, lines in the stack trace are doubled
  with and witout demanglind/addr2line

Attempt to dump locks
threadid=0x7ffaa63fe640 max=2 current=-1
threadid=0x7ffaa53fc640 max=3 current=-1
threadid=0x7ffaa5bfd640 max=0 current=-1
threadid=0x7ffaa6bff640 max=0 current=-1
threadid=0x7ffaa7a2a080 max=0 current=-1
Attempt to dump current JCRs. njcrs=1
threadid=0x7ffaa53fc640 JobId=2 JobStatus=R jcr=0x7ffa98025728 name=RestoreFiles.2024-02-07_19.45.34_04
        use_count=1 killable=1
        JobType=R JobLevel=F
        sched_time=07-Feb-2024 19:45 start_time=07-Feb-2024 19:45
        end_time=01-Jan-1970 01:00 wait_time=01-Jan-1970 01:00
        db=(nil) db_batch=(nil) batch_started=0
        dcr=0x7ffa98000908 volumename=TestVolume001 dev=0x7ffa9800bbe8 newvol=0 reserved=1 locked=0
List plugins. Hook count=0
    /home/bac/workspace/bee/regress/bin/libbacsd-18.0.0.so(_Z12read_recordsP3DCRPFbS0_P10DEV_RECORDEPFbS0_E+0x11b) [0x7ffaa806b275]
    /home/bac/workspace/bee/regress/bin/libbacsd-18.0.0.so:read_records(DCR*, bool (*)(DCR*, DEV_RECORD*), bool (*)(DCR*))
    /home/bac/workspace/bee/regress/bin/libbacsd-18.0.0.so(_Z12do_read_dataP3JCR+0x43c) [0x7ffaa80695f4]
    /home/bac/workspace/bee/regress/bin/libbacsd-18.0.0.so:do_read_data(JCR*)
    /home/bac/workspace/bee/regress/bin/bacula-sd(+0x234a7) [0x5558cd5db4a7]
    /home/bac/workspace/bee/regress/build/src/stored/fd_cmds.c:431
    /home/bac/workspace/bee/regress/bin/bacula-sd(+0x2281a) [0x5558cd5da81a]
    /home/bac/workspace/bee/regress/build/src/stored/fd_cmds.c:234
    /home/bac/workspace/bee/regress/bin/bacula-sd(+0x22473) [0x5558cd5da473]
    /home/bac/workspace/bee/regress/build/src/stored/fd_cmds.c:176
    /home/bac/workspace/bee/regress/bin/bacula-sd(+0x25025) [0x5558cd5dd025]
    /home/bac/workspace/bee/regress/build/src/stored/job.c:252
    /home/bac/workspace/bee/regress/bin/bacula-sd(+0x17f53) [0x5558cd5cff53]
    /home/bac/workspace/bee/regress/build/src/stored/dircmd.c:255
    /home/bac/workspace/bee/regress/bin/libbac-18.0.0.so(workq_server+0x45f) [0x7ffaa7f9e0fe]
    /home/bac/workspace/bee/regress/bin/libbac-18.0.0.so:workq_server()
    /home/bac/workspace/bee/regress/bin/libbac-18.0.0.so(lmgr_thread_launcher+0xf7) [0x7ffaa7faa2b4]
    /home/bac/workspace/bee/regress/bin/libbac-18.0.0.so:lmgr_thread_launcher()
    /lib/x86_64-linux-gnu/libc.so.6(+0x94ac3) [0x7ffaa7894ac3]
    ./nptl/pthread_create.c:442
    /lib/x86_64-linux-gnu/libc.so.6(+0x126850) [0x7ffaa7926850]
    ./misc/../sysdeps/unix/sysv/linux/x86_64/clone3.S:83

Please install GDB.