Fix return type of make_time.

Fix return type of make_time.

make_time is documented to return a (TICKS . HZ) pair, so we can’t use
make_lisp_time.  Introduce a new conversion function instead.

* src/emacs-module.c (module_make_time): Use timespec_to_lisp to
correct return type.

* src/timefns.c (timespec_to_lisp): New function.
(make_lisp_time): Use it.

* test/src/emacs-module-tests.el (mod-test-add-nanosecond/valid):
Check return type.