AU: Changes for deltas on traditional bios machines.

BUG=None
TEST=Attached unittests/tested on image

- Fix uninitialized variable err in action processor unittest

- Let Omaha dictate if an update is a delta or full update

- Bug fix in delta generator for differently-sized images

- More logging when applying delta updates

- Fix infinite loop in http fetcher unittest

- log each HTTP connection to know when a dropped connection is
  reestablished.

- Detect when speed goes below a threshold and reestablish HTTP
  connection (currently < 10bytes/sec for 90 contiguous seconds).

- Fix stack overflow in libcurl http fetcher.

- optimize out a lot of needless CPU usage in libcurl http fetcher
  (turns out adding a glib main loop source uses a lot of CPU).

- subprocess: pass PATH, log stdout/stderr

- postinstall runner: support for ext3 and ext4 target filesystems.

Review URL: http://codereview.chromium.org/2805027
diff --git a/delta_diff_generator.cc b/delta_diff_generator.cc
index 23c5fc8..ec07119 100644
--- a/delta_diff_generator.cc
+++ b/delta_diff_generator.cc
@@ -27,6 +27,7 @@
 #include "update_engine/utils.h"
 
 using std::make_pair;
+using std::max;
 using std::min;
 using std::set;
 using std::string;
@@ -756,7 +757,7 @@
   TEST_AND_RETURN_FALSE(utils::FileSize(old_kernel_part) >= 0);
   TEST_AND_RETURN_FALSE(utils::FileSize(new_kernel_part) >= 0);
 
-  vector<Block> blocks(min(old_image_stbuf.st_size / kBlockSize,
+  vector<Block> blocks(max(old_image_stbuf.st_size / kBlockSize,
                            new_image_stbuf.st_size / kBlockSize));
   LOG(INFO) << "invalid: " << Vertex::kInvalidIndex;
   LOG(INFO) << "len: " << blocks.size();