Allow sepolicies granting bootanim exec on /oem.

Iot would like to allow bootanim to load libraries from /oem but in order for
device-specfic sepolicies to grant exec this global restriction needs to
be relaxed.

Bug: 37992717
Test: Tested with Iot sepolicies in effect and bootanim can exec.
Change-Id: I6462bf510562eb3fb06304e50b68fba05d37b285