Demote the log in ProcessState.ensureNotDead from a wtf to a warning.

It's raising alarm bells but there isn't much we can do without a lot
of rewriting inside the ActivityManager.  The only consequence is stats
that are off by a little bit.

Bug: 28581070
Change-Id: If51568c3a708a907ceef6452e7d45599a57454f7

core/java/com/android/internal/app/procstats/ProcessState.java

@@ -277,7 +277,7 @@ public final class ProcessState {
         if (!mDead) {
             return;
         }
-        Slog.wtfStack(TAG, "ProcessState dead: name=" + mName
+        Slog.w(TAG, "ProcessState dead: name=" + mName
                 + " pkg=" + mPackage + " uid=" + mUid + " common.name=" + mCommonProcess.mName);
     }