stand: Install libsa.3

Turns out there is a libsa.3. It's a bit out of date, but we reference
it in a number of places so we should install it. We need to do the DO32
dance because this Makefile is included twice and we don't want it
installing twice.

Sponsored by: Netflix

(cherry picked from commit 70b5c4ff4807656307d1cb2f7193916ebab94893)