binder: Add an API to check if the threadpool has been started

Libraries that require the threadpool can check this to make sure the
threadpool has been started before it is needed.

Test: atest binderLibTest
Bug: 261652496
Change-Id: I7505319f162e2789dcc3c41bf1f7535c5c1bb9d9
diff --git a/libs/binder/ndk/process.cpp b/libs/binder/ndk/process.cpp
index ac582a4..bc6610e 100644
--- a/libs/binder/ndk/process.cpp
+++ b/libs/binder/ndk/process.cpp
@@ -31,6 +31,9 @@
 bool ABinderProcess_setThreadPoolMaxThreadCount(uint32_t numThreads) {
     return ProcessState::self()->setThreadPoolMaxThreadCount(numThreads) == 0;
 }
+bool ABinderProcess_isThreadPoolStarted() {
+    return ProcessState::self()->isThreadPoolStarted();
+}
 void ABinderProcess_joinThreadPool() {
     IPCThreadState::self()->joinThreadPool();
 }