Fix PR bootstrap/102389: --with-build-config=bootstrap-lto is broken

So the problem here is that now the lto-plugin requires NM that works
with LTO to work so we need to pass down NM just like we do for ranlib
and ar.

config/
	* bootstrap-lto-lean.mk: Handle NM like RANLIB AND AR.
	* bootstrap-lto.mk: Likewise.