libbinder: log when threads requested, not started

Few bugs about this over the years, so adding a log for
it.

Bug: 383234630
Test: no logs added on CF boot:
    `adb logcat -d | grep "Thread pool configuration"`
Change-Id: I14382ee5d7e9cd56c245eb6d3883e7db14ff935b
diff --git a/libs/binder/IPCThreadState.cpp b/libs/binder/IPCThreadState.cpp
index 6698d0c..623e7b9 100644
--- a/libs/binder/IPCThreadState.cpp
+++ b/libs/binder/IPCThreadState.cpp
@@ -775,6 +775,7 @@
 {
     LOG_THREADPOOL("**** THREAD %p (PID %d) IS JOINING THE THREAD POOL\n", (void*)pthread_self(),
                    getpid());
+    mProcess->checkExpectingThreadPoolStart();
     mProcess->mCurrentThreads++;
     mOut.writeInt32(isMain ? BC_ENTER_LOOPER : BC_REGISTER_LOOPER);