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/base/variant_map_test.cc b/runtime/base/variant_map_test.cc
index f306a48..ccb22eb 100644
--- a/runtime/base/variant_map_test.cc
+++ b/runtime/base/variant_map_test.cc
@@ -18,7 +18,7 @@
 #include "gtest/gtest.h"
 
 #define EXPECT_NULL(expected) EXPECT_EQ(reinterpret_cast<const void*>(expected), \
-                                        reinterpret_cast<void*>(NULL));
+                                        static_cast<void*>(nullptr));
 
 namespace art {