arm64 system clang & llvm

context is main-n267804 arm64

I'd like to avoid building base compilers for arches I'll never use.
I want aarch64 *only*

To achieve this, there's the following in /etc/src.conf

###
# LLVM
WITHOUT_LLVM_TARGET_ALL=
WITH_LLVM_TARGET_AARCH64=
WITHOUT_LLVM_TARGET_ARM=
WITHOUT_LLVM_ASSERTIONS=

But looking at buildworld output, I see what *looks* like building for 
other arches happening. Is this the case, or am I reading it wrong, or
is the src.conf wrong?

thanks in advance,
--