Add lazy loading support to libstatssocket.
There are many clients of libstatssocket (lmkd, surfaceflinger,
bootanimation dependencies) that run before the statsd apex is mounted
and cannot link libstatssocket.so when the process starts. Lazy loading
will load the library when the logging apis get called.
This change is modeled heavily off of aosp/1570701, which added
libnativehelper_lazy.
Bug: 178480419
Test: atest libstatssocket_lazy_test
Change-Id: I57e6f698ad43dddc98dc787ba2fe888030c8a282
