Re-add compile_multilib to statsd apex

An earlier revert removed compile_multilib: both line which caused only
64-bit variant of libstats_jni to be added to the apex when 32-bit is
also required.

This change adds both 32-bit and 64-bit variants to the apex.

Bug: 149720256
Test: m
Test: fastboot flashall
Test: launch Play Store
Change-Id: I594b290e60052e28139cd954a54ada1067d43e09