medialog: add missing call to join binder thread pool

Bug: 27816096
Change-Id: I4ec4a5bdb98a793554fc8c3cc01c2a897d11adf0
diff --git a/media/audioserver/main_audioserver.cpp b/media/audioserver/main_audioserver.cpp
index 698da1f..4a7a988 100644
--- a/media/audioserver/main_audioserver.cpp
+++ b/media/audioserver/main_audioserver.cpp
@@ -56,6 +56,7 @@
         sp<ProcessState> proc(ProcessState::self());
         MediaLogService::instantiate();
         ProcessState::self()->startThreadPool();
+        IPCThreadState::self()->joinThreadPool();
         for (;;) {
             siginfo_t info;
             int ret = waitid(P_PID, childPid, &info, WEXITED | WSTOPPED | WCONTINUED);