Subzero: Fix a build error. Also reformat.

src/IceMemory.h

 //===- subzero/src/IceMemory.h - Memory management declarations -*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 126 matching lines @@
 public:
   using allocator_type = ArenaAllocator *;
   using manager_type = Cfg;
   static constexpr bool cache_allocator = false;
 
   static void init() { ICE_TLS_INIT_FIELD(CfgAllocator); };
 
   static allocator_type current();
   static void set_current(const manager_type *Manager);
   static void set_current(ArenaAllocator *Allocator);
-  static void set_current(nullptr_t);
+  static void set_current(std::nullptr_t);
 
 private:
   ICE_TLS_DECLARE_FIELD(ArenaAllocator *, CfgAllocator);
 };
 
 template <typename T>
 using CfgLocalAllocator = sz_allocator<T, CfgAllocatorTraits>;
 
 using CfgLocalAllocatorScope = sz_allocator_scope<CfgAllocatorTraits>;
 
@@ skipping 18 matching lines @@
 };
 
 template <typename T>
 using LivenessAllocator = sz_allocator<T, LivenessAllocatorTraits>;
 
 using LivenessAllocatorScope = sz_allocator_scope<LivenessAllocatorTraits>;
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEMEMORY_H