Revert attempt to use 'noexcept' in typedef

Revert attempt to use 'noexcept' in typedef

This use of 'noexcept' runs afoul of the C++11 standard.
Problem reported by Philipp Stephani in:
http://lists.gnu.org/archive/html/emacs-devel/2016-01/msg00706.html
* src/emacs-module.c (emacs_finalizer_function):
Move this typedef here ...
* src/emacs-module.h: ... from here, and use only the C
version of the typedef.  The typedef is now private since it
is never used in the .h file now and anyway it seemed to be
causing more confusion than it cured.
(make_user_ptr, get_user_finalizer, set_user_finalizer):
Open-code the type instead.