Build+test bn_mp_set_double.c on more platforms
Not all platforms/environments/architectures that support enough of
IEEE 754 for the purposes of mp_set_double() actually support enough
to legitimately define __STDC_IEC_559__, so only relying on that is
too strict. Fixes https://github.com/libtom/libtommath/issues/159
Execute move.sh - Rename files from bn_* to match the function names.
* git blame <renamed-file> is not affected
* git log --follow <renamed-file> can be used to show log across renames
