Replace NULL with nullptr

Also fixed some lines that were too long, and a few other minor
details.

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/runtime/monitor_android.cc b/runtime/monitor_android.cc
index d89290b..48c9cce 100644
--- a/runtime/monitor_android.cc
+++ b/runtime/monitor_android.cc
@@ -88,7 +88,7 @@
   cp = EventLogWriteInt(cp, line_number);
 
   // Emit the lock owner source code file name, <= 37 bytes.
-  if (owner_filename == NULL) {
+  if (owner_filename == nullptr) {
     owner_filename = "";
   } else if (strcmp(filename, owner_filename) == 0) {
     // Common case, so save on log space.