Ensure that noexcept(false) is used for the dtor that can throw exceptions
when using MSVS 2015, otherwise the program would simply abort when it
happened.

Also rename SOCI_ONCE_TEMP_TYPE_NOEXCEPT macro to a more generic
SOCI_NOEXCEPT_FALSE in case we need to reuse it elsewhere and define it in
soci-platform.h.