update OTA package maker to do whole-file signature

Use the new -w flag to SignApk when signing OTA packages.
diff --git a/tools/releasetools/ota_from_target_files b/tools/releasetools/ota_from_target_files
index 864c35b..dbb38f2 100755
--- a/tools/releasetools/ota_from_target_files
+++ b/tools/releasetools/ota_from_target_files
@@ -273,7 +273,8 @@
   key_passwords = common.GetKeyPasswords([OPTIONS.package_key])
   pw = key_passwords[OPTIONS.package_key]
 
-  common.SignFile(temp_zip_name, output_zip_name, OPTIONS.package_key, pw)
+  common.SignFile(temp_zip_name, output_zip_name, OPTIONS.package_key, pw,
+                  whole_file=True)
 
 
 def AppendAssertions(script, input_zip):