depends: don't restrict --enable-lto to non-guix cctools

This wasn't actually disabling LTO support anyways, because it's enabled
by default.

depends/packages/native_cctools.mk

@@ -7,11 +7,9 @@ $(package)_build_subdir=cctools
 $(package)_dependencies=native_libtapi
 
 define $(package)_set_vars
-  $(package)_config_opts=--target=$(host)
+  $(package)_config_opts=--target=$(host) --enable-lto-support
+  $(package)_config_opts+=--with-llvm-config=$(llvm_config_prog)
   $(package)_ldflags+=-Wl,-rpath=\\$$$$$$$$\$$$$$$$$ORIGIN/../lib
-  ifeq ($(strip $(FORCE_USE_SYSTEM_CLANG)),)
-  $(package)_config_opts+=--enable-lto-support --with-llvm-config=$(build_prefix)/bin/llvm-config
-  endif
   $(package)_cc=$(clang_prog)
   $(package)_cxx=$(clangxx_prog)
 endef