servicemanager: avoid segfault on null manifest.

A device like this should fail VTS or other tests, but a segfault is
counterproductive.

Bug: 143744480
Test: TH
Change-Id: I71c42f1f8d5288152c6db43c33f44a7235df1265
diff --git a/cmds/servicemanager/ServiceManager.cpp b/cmds/servicemanager/ServiceManager.cpp
index 91e89ae..861401c 100644
--- a/cmds/servicemanager/ServiceManager.cpp
+++ b/cmds/servicemanager/ServiceManager.cpp
@@ -50,7 +50,7 @@
             vintf::VintfObject::GetDeviceHalManifest(),
             vintf::VintfObject::GetFrameworkHalManifest()
         }) {
-        if (manifest->hasAidlInstance(package, iface, instance)) {
+        if (manifest != nullptr && manifest->hasAidlInstance(package, iface, instance)) {
             return true;
         }
     }