Fix relabeling of secondary user package directories.

When relabeling secondary user package directories, we need to use
the uid of the directory rather than the primary package UID;
otherwise, levelFrom=user will not work correctly.

Change-Id: I0d76ec6ec6fe56a566023ca5e1398efdf28fc81e
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>