update_engine: Generate PUFFDIFF operation

This patch adds functionality for generating PUFFDIFF operation, but
since the minor verion has not been increase, it actually does not
generate the operation itself. PUFFDIFF is used for patching deflate
based files.

BUG=chromium:767120
TEST=unittest passes; brillo_update_payload {generate|verify} passes;
CQ-DEPEND=CL:726945

Change-Id: I4ffdac8dce3740ef9fc2156cb0dad83a8364c8b5
Reviewed-on: https://chromium-review.googlesource.com/658298
Commit-Ready: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
diff --git a/Android.mk b/Android.mk
index fcde4f5..08798aa 100644
--- a/Android.mk
+++ b/Android.mk
@@ -611,8 +611,9 @@
 # for any client code.
 ue_libpayload_generator_exported_static_libraries := \
     libbsdiff \
-    libpayload_consumer \
     liblzma \
+    libpayload_consumer \
+    libpuffdiff \
     update_metadata-protos \
     $(ue_libpayload_consumer_exported_static_libraries) \
     $(ue_update_metadata_protos_exported_static_libraries)
@@ -661,8 +662,9 @@
 LOCAL_C_INCLUDES := $(ue_common_c_includes)
 LOCAL_STATIC_LIBRARIES := \
     libbsdiff \
-    libpayload_consumer \
     liblzma \
+    libpayload_consumer \
+    libpuffdiff \
     update_metadata-protos \
     $(ue_common_static_libraries) \
     $(ue_libpayload_consumer_exported_static_libraries) \