Replace NULL with nullptr

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

Change-Id: I6efba5fb6e03eb5d0a300fddb2a75bf8e2f175cb
diff --git a/compiler/compiled_method.cc b/compiler/compiled_method.cc
index 4f7a970..d1acada 100644
--- a/compiler/compiled_method.cc
+++ b/compiler/compiled_method.cc
@@ -108,7 +108,7 @@
     }
     default:
       LOG(FATAL) << "Unknown InstructionSet: " << instruction_set;
-      return NULL;
+      return nullptr;
   }
 }