Fix CMP0054 warning

git-svn-id: https://svn.hdfgroup.uiuc.edu/hdf5/trunk@25904 dab4d1a6-ed17-0410-a064-d1ae371a2980
Fix CMP0054 warning

git-svn-id: https://svn.hdfgroup.uiuc.edu/hdf5/trunk@25905 dab4d1a6-ed17-0410-a064-d1ae371a2980