Unsupported ar option -f on MacOS

Hi,

It seems like ar option -f is not supported on MacOS's (which comes from LLVM) ar(1).

ar -frsv libuefi.a dirent.o qsort.o stat.o stdio.o stdlib.o string.o time.o unistd.o >/dev/null
/Library/Developer/CommandLineTools/usr/bin/ar: illegal option -- f

It can be easily workaround by switching to binutils's AR or just removing -f.

I just wonder if this option is absolutely necessary for us?

Thanks