rename HDF5_*_LIBRARY to HDF5_*_LIBRARIES

This makes sure that netCDF plays nicely with FindHDF5.cmake
from CMake.

Conflicts:
	liblib/CMakeLists.txt
Merge branch 'cmake-hdf5-variable-names' of https://github.com/nschloe/netcdf-c into nschloe-cmake-hdf5-variable-names
Merge branch 'nschloe-cmake-hdf5-variable-names'