Merge "Remove unused-but-set-{variable,parameter} from ClangUnknownCflags" am: 861441fa36 am: 910cf32f49

Original change: https://android-review.googlesource.com/c/platform/build/soong/+/1824620

Change-Id: I642c95426a532f93cfe52dcab2c199e7891ef1cc