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/entrypoints/interpreter/interpreter_entrypoints.cc b/runtime/entrypoints/interpreter/interpreter_entrypoints.cc
index 28e19d4..d4844c2 100644
--- a/runtime/entrypoints/interpreter/interpreter_entrypoints.cc
+++ b/runtime/entrypoints/interpreter/interpreter_entrypoints.cc
@@ -47,7 +47,7 @@
       method = shadow_frame->GetMethod();
     }
   }
-  uint16_t arg_offset = (code_item == NULL) ? 0 : code_item->registers_size_ - code_item->ins_size_;
+  uint16_t arg_offset = (code_item == nullptr) ? 0 : code_item->registers_size_ - code_item->ins_size_;
   method->Invoke(self, shadow_frame->GetVRegArgs(arg_offset),
                  (shadow_frame->NumberOfVRegs() - arg_offset) * sizeof(uint32_t),
                  result, method->GetShorty());