PetscViewerCreate_HDF5: check viewer is serial if HDF5 is serial
to prevent unclear errors like
HDF5-DIAG: Error detected in HDF5 (1.12.1) thread 0:
...
#006: H5FDsec2.c line 1002 in H5FD__sec2_lock(): unable to lock file, errno = 35, error message = 'Resource temporarily unavailable'
major: Virtual File Layer
minor: Unable to lock file
Edited by Vaclav Hapla