Allow libstatssocket to be dynamically loaded

This cl was submitted to aosp/internal master in march, but was
mistakenly not cherry picked into rvc-dev.

This change is needed for libstatspush_compat to properly function on R
devices.

Test: m com.android.resolv
Test: verified netd/libnetd_resolv dlopen libstatssocket successfully
Test: adb shell cmd stats print-stats shows atom 116 is being logged
Bug: 160617623
Bug: 149229317
Change-Id: I55740632a4aae889505231efeeebe2809a659a7a
Merged-In: I55740632a4aae889505231efeeebe2809a659a7a