First, remove the unnecessary locale push & pop on <CT_TIME64>load.
Second, the registry accesses were caused by using g_win32_get_locale
to convert the Microsoft locale strings to POSIX ones. We don't care
what kind of string we get as long as we can pass it back to setlocale,
so remove that.
Third, gnc_push/pop_locale were used only in backend/dbi in a
very limited way and did much more than was necessary, so
convert them to C++ inlines in gnc-backend-dbi.hpp that does
only what we need them to.
cad6bb4272