Do not try to link HDF5 static

The problem here is more cumbersome. some libraries like libdl are
also included by MPI and would be linked once static once dynamic.
upgrading MPI to static binding is to intrusive so we stay with libSplash
static only and everything else "default".
Add Comments About the Disabled HDF5
Merge pull request #307 from ax3l/fix-SplashCMakeHDF5

Do not try to link HDF5 static