Fix more MSVC warnings, courgette/ edition.

courgette/disassembler_win32_x64.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "courgette/disassembler_win32_x64.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 555 matching lines @@
         p += relocs_size;
         continue;
       }
     }
 
     while (abs32_pos != abs32_locations_.end() && *abs32_pos < current_rva)
       ++abs32_pos;
 
     if (abs32_pos != abs32_locations_.end() && *abs32_pos == current_rva) {
       uint32 target_address = Read32LittleEndian(p);
-      RVA target_rva = target_address - image_base();
+      // TODO(wfh): image_base() can be larger than 32 bits, so this math can
+      // underflow.  Figure out the right solution here.
+      RVA target_rva = target_address - static_cast<uint32>(image_base());
       // TODO(sra): target could be Label+offset.  It is not clear how to guess
       // which it might be.  We assume offset==0.
       if (!program->EmitAbs32(program->FindOrMakeAbs32Label(target_rva)))
         return false;
       p += 4;
       continue;
     }
 
     while (rel32_pos != rel32_locations_.end() && *rel32_pos < current_rva)
       ++rel32_pos;
@@ skipping 136 matching lines @@
     directory->size_ = static_cast<uint32>(size);
     return true;
   } else {
     directory->address_ = 0;
     directory->size_ = 0;
     return true;
   }
 }
 
 }  // namespace courgette