Don't initialize ProcessState without /dev/hwbinder.

To prevent creating ProcessState objects on devices
that don't have hwbinder.

Change-Id: I4e5bea68f55d007228382699311ccd74a50391d5
diff --git a/IServiceManager.cpp b/IServiceManager.cpp
index fd0e485..5bb6b92 100644
--- a/IServiceManager.cpp
+++ b/IServiceManager.cpp
@@ -35,7 +35,11 @@
 sp<IServiceManager> defaultServiceManager()
 {
     if (gDefaultServiceManager != NULL) return gDefaultServiceManager;
-
+    if (access("/dev/hwbinder", F_OK) != 0) {
+        // HwBinder not available on this device or not accessible to
+        // this process.
+        return nullptr;
+    }
     {
         AutoMutex _l(gDefaultServiceManagerLock);
         while (gDefaultServiceManager == NULL) {