FIXED: workaround Emacs incompatibility with certain locales

FIXED: workaround Emacs incompatibility with certain locales

The Emacs Elisp reader only works with locales that have "." as their
decimal separator, but Prolog initialization sets up the locale
according to the environment variables.  Therefore we need to reset
the locale after initializing Prolog in case the environment
prescribes a locale with a different decimal separator, such as fr_FR.
See also https://github.com/SWI-Prolog/packages-sweep/issues/1