COMP: HDF5 library version variables contain '@'.

A future version of CMake may disallow @VAR@ variable references
in CMake code.  Use ${VAR} variable reference syntax instead.

Change-Id: I727096b57651f1ebd3ec542dd4ce92f51aa2560b
Merge topic 'cmake-variable-names'

22751ad8 COMP: HDF5 library version variables contain '@'.