Treat it dead if the process record's pid is invalid

Bug: 146430891
Test: Manual
Change-Id: I98bf86d2a0ee2be2ecdd613e547dbdb0fd621e95

services/core/java/com/android/server/am/ProcessList.java

@@ -2101,6 +2101,10 @@ public final class ProcessList {
      */
     @GuardedBy("mService")
     private boolean isProcessAliveLiteLocked(ProcessRecord app) {
+        // If somehow the pid is invalid, let's think it's dead.
+        if (app.pid <= 0) {
+            return false;
+        }
         try {
             Os.kill(app.pid, 0);
         } catch (ErrnoException e) {