I've googled this and learned that watering plants with a little of seawater (with 3,5% of salt) is actually good for them if you want them to bloom faster, but too much kills them, so if seawater and water in human tears both have salt it depends on how much someone is crying I guess. xD
I tried to find how much salt is in human tears but only learned they sell this stuff as seasoning? o.e