system_server: Report dalvikcache_data_file execute violations.

With build/core eaa9d88cf, system_server should not be loading code
from /data. Add an auditallow rule to report violations.

Bug: 37214733
Test: Boot marlin, no SELinux audit lines for system_server.
Change-Id: I2e25eb144503274025bd4fc9bb519555851f6521
(cherry picked from commit 665128fa)