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/utils/mips64/assembler_mips64.h b/compiler/utils/mips64/assembler_mips64.h
index 36e74d7..b7f6a9e 100644
--- a/compiler/utils/mips64/assembler_mips64.h
+++ b/compiler/utils/mips64/assembler_mips64.h
@@ -235,14 +235,14 @@
   void GetCurrentThread(ManagedRegister tr) OVERRIDE;
   void GetCurrentThread(FrameOffset dest_offset, ManagedRegister mscratch) OVERRIDE;
 
-  // Set up out_reg to hold a Object** into the handle scope, or to be NULL if the
+  // Set up out_reg to hold a Object** into the handle scope, or to be null if the
   // value is null and null_allowed. in_reg holds a possibly stale reference
   // that can be used to avoid loading the handle scope entry to see if the value is
-  // NULL.
+  // null.
   void CreateHandleScopeEntry(ManagedRegister out_reg, FrameOffset handlescope_offset,
                               ManagedRegister in_reg, bool null_allowed) OVERRIDE;
 
-  // Set up out_off to hold a Object** into the handle scope, or to be NULL if the
+  // Set up out_off to hold a Object** into the handle scope, or to be null if the
   // value is null and null_allowed.
   void CreateHandleScopeEntry(FrameOffset out_off, FrameOffset handlescope_offset, ManagedRegister
                               mscratch, bool null_allowed) OVERRIDE;