Inline DISALLOW_COPY_AND_ASSIGN.

snappy-stubs-public.h defined the DISALLOW_COPY_AND_ASSIGN macro, so the
definition propagated to all translation units that included the open
source headers. The macro is now inlined, thus avoiding polluting the
macro environment of snappy users.

snappy-stubs-internal.h

@@ -350,7 +350,9 @@ class Bits {
   static int FindLSBSetNonZero64(uint64 n);
 
  private:
-  DISALLOW_COPY_AND_ASSIGN(Bits);
+  // No copying
+  Bits(const Bits&);
+  void operator=(const Bits&);
 };
 
 #ifdef HAVE_BUILTIN_CTZ