nmtst_main_context_iterate_until() is a macro, and we don't want to restrict the
valid integer type (or range) of the "timeout_msec" argument.
In particular, if the user calculates a timeout with "timestamp_msec -
now_msec", the resulting "timeout_msec" might be a negative gint64.
We should handle that gracefully, and not let it be cast to a huge
unsigned int.
(cherry picked from commit 6cb6888404)
(cherry picked from commit 4d572bea7e)
(cherry picked from commit 95b74a3bde)
(cherry picked from commit 500c63db3c)
(cherry picked from commit e8a5cee1a1)
(cherry picked from commit c909149c13)
5373680df9