logd: Add pidToName helper

Change-Id: Idd8e804ab65feb8dc432150ae701464de1ad5302
diff --git a/logd/LogBuffer.h b/logd/LogBuffer.h
index c3460ca..7c57660 100644
--- a/logd/LogBuffer.h
+++ b/logd/LogBuffer.h
@@ -77,6 +77,9 @@
     void formatPrune(char **strp) { mPrune.format(strp); }
 #endif
 
+    // helper
+    char *pidToName(pid_t pid) { return stats.pidToName(pid); }
+
 private:
     void maybePrune(log_id_t id);
     void prune(log_id_t id, unsigned long pruneRows);