Deletion of files in jhdf5-db fails

[t-erxleben]

The file specific callback is not implemented but needed for deletion.
On top one of the arguments is used unchecked but may be null (as it is the case here).

https://github.com/julea-io/julea/blob/68dbd67c53c459af437495f0a9988b567ad5f8a0/lib/hdf5-db/jhdf5-db-file.c#L414

Stack trace:

Thread 1 "julea-test" received signal SIGSEGV, Segmentation fault.
0x00007ffff2d92297 in H5VL_julea_db_file_specific (obj=0x0, specific_type=<optimized out>, dxpl_id=<optimized out>, req=<optimized out>, arguments=<optimized out>) at ../lib/hdf5-db/jhdf5-db-file.c:414
414             g_return_val_if_fail(object->type == J_HDF5_OBJECT_TYPE_FILE, 1);
(gdb) bt
#0  0x00007ffff2d92297 in H5VL_julea_db_file_specific (obj=0x0, specific_type=<optimized out>, dxpl_id=<optimized out>, req=<optimized out>, arguments=<optimized out>)
    at ../lib/hdf5-db/jhdf5-db-file.c:414
#1  0x00007ffff6e899e3 in H5VL__file_specific (cls=<optimized out>, arguments=0x7ffffffef4b8, req=0x0, dxpl_id=792633534417207304, specific_type=H5VL_FILE_IS_ACCESSIBLE, obj=0x0)
    at /tmp/timm/spack-stage/spack-stage-hdf5-1.12.1-fnik2jepmxvtfdengvfpqda5556jtgxm/spack-src/src/H5VLcallback.c:3698
#2  H5VL_file_specific (vol_obj=vol_obj@entry=0x0, specific_type=specific_type@entry=H5VL_FILE_IS_ACCESSIBLE, dxpl_id=792633534417207304, req=req@entry=0x0)
    at /tmp/timm/spack-stage/spack-stage-hdf5-1.12.1-fnik2jepmxvtfdengvfpqda5556jtgxm/spack-src/src/H5VLcallback.c:3768
#3  0x00007ffff6ca1c19 in H5Fdelete (filename=filename@entry=0x555555596560 "test_file.h5", fapl_id=<optimized out>, fapl_id@entry=0)
    at /tmp/timm/spack-stage/spack-stage-hdf5-1.12.1-fnik2jepmxvtfdengvfpqda5556jtgxm/spack-src/src/H5F.c:758
#4  0x000055555558023f in test_hdf_file_create_delete () at ../test/hdf5/hdf-file.c:59
#5  0x00007ffff72cffd6 in g_test_run_suite_internal ()
   from /home/timm/Projects/julea/dependencies/opt/spack/linux-ubuntu20.04-ivybridge/gcc-9.3.0/glib-2.68.3-jafnk6426z6ijq33a46frgv6j2bqtpfo/lib/libglib-2.0.so.0
#6  0x00007ffff72cfd25 in g_test_run_suite_internal ()
   from /home/timm/Projects/julea/dependencies/opt/spack/linux-ubuntu20.04-ivybridge/gcc-9.3.0/glib-2.68.3-jafnk6426z6ijq33a46frgv6j2bqtpfo/lib/libglib-2.0.so.0
#7  0x00007ffff72d050b in g_test_run_suite () from /home/timm/Projects/julea/dependencies/opt/spack/linux-ubuntu20.04-ivybridge/gcc-9.3.0/glib-2.68.3-jafnk6426z6ijq33a46frgv6j2bqtpfo/lib/libglib-2.0.so.0
#8  0x00007ffff72d0566 in g_test_run () from /home/timm/Projects/julea/dependencies/opt/spack/linux-ubuntu20.04-ivybridge/gcc-9.3.0/glib-2.68.3-jafnk6426z6ijq33a46frgv6j2bqtpfo/lib/libglib-2.0.so.0
#9  0x000055555558ea49 in main (argc=<optimized out>, argv=<optimized out>) at ../test/test.c:77```