[upstream_utils] Remove git version from upstream patches (#4351)

This reduces commit noise when other git versions are used. The version
was removed by passing `--no-signature` to `git format-patch` which is
now documented in the readme.

upstream_utils/llvm_patches/0010-Remove-unused-functions.patch

@@ -738,6 +738,3 @@ index bff7b6c9a77b..611043dc5925 100644
 -
 -  return Temp->keep(OutputFileName);
 -}
--- 
-2.20.1.windows.1
-