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/jit/jit_code_cache.h b/runtime/jit/jit_code_cache.h
index 8a20e39..da891fe 100644
--- a/runtime/jit/jit_code_cache.h
+++ b/runtime/jit/jit_code_cache.h
@@ -86,10 +86,10 @@
   // Return true if the code cache contains a code ptr.
   bool ContainsCodePtr(const void* ptr) const;
 
-  // Reserve a region of code of size at least "size". Returns nullptr if there is no more room.
+  // Reserve a region of code of size at least "size". Returns null if there is no more room.
   uint8_t* ReserveCode(Thread* self, size_t size) LOCKS_EXCLUDED(lock_);
 
-  // Add a data array of size (end - begin) with the associated contents, returns nullptr if there
+  // Add a data array of size (end - begin) with the associated contents, returns null if there
   // is no more room.
   uint8_t* AddDataArray(Thread* self, const uint8_t* begin, const uint8_t* end)
       LOCKS_EXCLUDED(lock_);