Removes H5detect and H5make_libsettings from the build and replaces
their functionality with things that don't affect cross-compiling.
H5detect --> floating-point types are now detected on library load
H5make_libsettings --> Moved functionality to a new H5build_settings.c template file
machines (where tests are to be run as batch jobs.
Add README_HPC file with instructions for setting up configuration
to use batch scripts for running tests on HPC machines and some
pointers for cross compiling.
