Add zucchini support in update_engine

Support zucchini as a diff algorithm in delta generator.
Note we won't update the max support version until the
installation support is in place.

Bug: 197361113
Test: TH, generate a diff package
Change-Id: I92db1e7ab2ac4aef104a715c089b136f138064e9

scripts/update_payload/common.py

diff --git a/scripts/update_payload/common.py b/scripts/update_payload/common.py
index b934cf8..7c6ec8f 100644
--- a/scripts/update_payload/common.py
+++ b/scripts/update_payload/common.py
@@ -62,8 +62,9 @@
   REPLACE_XZ = _CLASS.REPLACE_XZ
   PUFFDIFF = _CLASS.PUFFDIFF
   BROTLI_BSDIFF = _CLASS.BROTLI_BSDIFF
+  ZUCCHINI = _CLASS.ZUCCHINI
   ALL = (REPLACE, REPLACE_BZ, SOURCE_COPY, SOURCE_BSDIFF, ZERO,
-         DISCARD, REPLACE_XZ, PUFFDIFF, BROTLI_BSDIFF)
+         DISCARD, REPLACE_XZ, PUFFDIFF, BROTLI_BSDIFF, ZUCCHINI)
   NAMES = {
       REPLACE: 'REPLACE',
       REPLACE_BZ: 'REPLACE_BZ',
@@ -74,6 +75,7 @@
       REPLACE_XZ: 'REPLACE_XZ',
       PUFFDIFF: 'PUFFDIFF',
       BROTLI_BSDIFF: 'BROTLI_BSDIFF',
+      ZUCCHINI: 'ZUCCHINI',
   }
 
   def __init__(self):