Correct double-convert from uid to userid

This was making readMasterKey and writeMasterKey always operate on
user 0, because of a double-division - getUserState(*) already
takes into account that the argument is a uid.

Fixes a number of issues related to multi-user and keystore; works
toward fixing bug 16233206.

(cherry picked from commit 50122db50bcb6c1aab50ef235c8f9d264b50e97a)

Change-Id: Ia1434fd0d076b0c36d383ff7390b17c78d7811b5
Merge "Correct double-convert from uid to userid"
Build keystore in 32 bit on platforms that require it.

Change-Id: I29543f72ef677870aa3f108c1ae4cb029df2f871
Merge "Build keystore in 32 bit on platforms that require it."
Comment out unused parameter.

BUG: 17281763
Change-Id: I1881e31893cd2d84389e4b29a4408d58654c20ca
Merge "Comment out unused parameter."