Update genrule to avoid patch on update

Fold the sed command into UPDATING into the genrule, so
upstream source can be used as is.

Bug: 291253039
Test: ./UPDATING e28988ecaa5e72523a982915084c9422e495116d # no change
Test: m libbssl_ffi
Change-Id: I0d2ad4baa7933d5420a7c0a9e8a974945bc664d8
3 files changed