updated hdf5 CMake: enable by default, made build dependent on if header and library found
updated hdf5 CMake: enable by default, made build dependent on if header and library found

ketchupok/csound,ketchupok/csound,csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,csound/csound,csound/csound,csound/csound,csound/csound,csound/csound,ketchupok/csound,csound/csound,ketchupok/csound,ketchupok/csound,ketchupok/csound,ketchupok/csound,csound/csound,csound/csound,ketchupok/csound