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/dex/quick/ralloc_util.cc b/compiler/dex/quick/ralloc_util.cc
index e779479..8ec86fa 100644
--- a/compiler/dex/quick/ralloc_util.cc
+++ b/compiler/dex/quick/ralloc_util.cc
@@ -935,7 +935,7 @@
       RegStorage my_reg = info->GetReg();
       RegStorage partner_reg = info->Partner();
       RegisterInfo* partner = GetRegInfo(partner_reg);
-      DCHECK(partner != NULL);
+      DCHECK(partner != nullptr);
       DCHECK(partner->IsWide());
       DCHECK_EQ(my_reg.GetReg(), partner->Partner().GetReg());
       DCHECK(partner->IsLive());