kbuild: remove sed command from cmd_ar_builtin

Replace a pipeline of echo and sed with printf to decrease process forks.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

scripts/Makefile.build

@@ -358,9 +358,8 @@ $(subdir-modorder): $(obj)/%/modules.order: $(obj)/% ;
 
 quiet_cmd_ar_builtin = AR      $@
       cmd_ar_builtin = rm -f $@; \
-		echo $(patsubst $(obj)/%,%,$(real-prereqs)) | \
-		sed -E 's:([^ ]+):$(obj)/\1:g' | \
-		xargs $(AR) cDPrST $@
+	$(if $(real-prereqs), printf "$(obj)/%s " $(patsubst $(obj)/%,%,$(real-prereqs)) | xargs) \
+	$(AR) cDPrST $@
 
 $(obj)/built-in.a: $(real-obj-y) FORCE
 	$(call if_changed,ar_builtin)