Simplify making restat rules by adding a --write_if_changed argument
to soong_zip that generates the output file into memory and then
compares it to the version on disk before writing it out.
Test: builds
Change-Id: I5059a1e3a11e79b0ca538b3b829bc7479c126ce6
to make it faster/easier to invoke from other Go programs
(such as multiproduct_kati)
Bug: 67478260
Test: m -j
Change-Id: Idd2671a44290550197c88f53dd11a6dd39c85cc5