AU: Class to perform delta updates.

A class to perform delta updates and the associated unittests. Also,
change the delta diff generator executable to be able to apply a
delta, which is handy for debugging.

TEST=Attached unit test, hand-tested on real build images
BUG=552

Review URL: http://codereview.chromium.org/1718001
diff --git a/extent_mapper.cc b/extent_mapper.cc
index 4af5f5d..e02f5a2 100755
--- a/extent_mapper.cc
+++ b/extent_mapper.cc
@@ -58,14 +58,14 @@
     rc = ioctl(fd, FIBMAP, &block32);
     TEST_AND_RETURN_FALSE_ERRNO(rc == 0);
     
-    const uint64 block = (block32 == 0 ? kSparseHole : block32);
+    const uint64_t block = (block32 == 0 ? kSparseHole : block32);
     
     graph_utils::AppendBlockToExtents(out, block);
   }
   return true;
 }
 
-bool GetFilesystemBlockSize(const std::string& path, uint32* out_blocksize) {
+bool GetFilesystemBlockSize(const std::string& path, uint32_t* out_blocksize) {
   int fd = open(path.c_str(), O_RDONLY, 0);
   TEST_AND_RETURN_FALSE_ERRNO(fd >= 0);
   ScopedFdCloser fd_closer(&fd);