Let breakpad build with -Wall on OS X and Linux.

src/common/linux/synth_elf.h

 // -*- mode: C++ -*-
 
 // Copyright (c) 2011, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
@@ skipping 155 matching lines @@
   SymbolTable(Endianness endianness, size_t addr_size, StringTable& table);
 
   // Add an Elf32_Sym.
   void AddSymbol(const string& name, uint32_t value,
                  uint32_t size, unsigned info, uint16_t shndx);
   // Add an Elf64_Sym.
   void AddSymbol(const string& name, uint64_t value,
                  uint64_t size, unsigned info, uint16_t shndx);
 
  private:
+#ifndef NDEBUG
   size_t addr_size_;
+#endif
   StringTable& table_;
 };
 
 // A class for note sections
 class Notes : public Section {
 public:
   Notes(Endianness endianness)
   : Section(endianness) {
   }
 
   // Add a note.
   void AddNote(int type, const string &name, const uint8_t* desc_bytes,
                size_t desc_size);
 };
 
 }  // namespace synth_elf
 }  // namespace google_breakpad
 
 #endif  // COMMON_LINUX_SYNTH_ELF_H_