refactor: move common parts of libselinux builds into defaults

Bug: 37343404
Bug: 37919668
Test: Build and boot

(cherry-picked from commit 51428ba055e581461e440331d3ccdb1bc4ac41c8)

Change-Id: I5e94788cac0c1574a74d75d9bd10589a760c4782
Merged-In: If42d24d381839c2a39f8cff3fc82ce5d3073eeb7
2 files changed