bpfilter: use 'userprogs' syntax to build bpfilter_umh

The user mode helper should be compiled for the same architecture as
the kernel.

This Makefile reused the 'hostprogs' syntax by overriding HOSTCC with CC.
Use the new syntax 'userprogs' to fix the Makefile mess.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Sam Ravnborg <sam@ravnborg.org>

net/bpfilter/Makefile

@@ -3,18 +3,14 @@
 # Makefile for the Linux BPFILTER layer.
 #
 
-hostprogs := bpfilter_umh
+userprogs := bpfilter_umh
 bpfilter_umh-objs := main.o
-KBUILD_HOSTCFLAGS += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \
-			$(filter -m32 -m64, $(KBUILD_CFLAGS))
-HOSTCC := $(CC)
+userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi
 
-ifeq ($(CONFIG_BPFILTER_UMH), y)
-# builtin bpfilter_umh should be compiled with -static
+# builtin bpfilter_umh should be linked with -static
 # since rootfs isn't mounted at the time of __init
 # function is called and do_execv won't find elf interpreter
-KBUILD_HOSTLDFLAGS += -static $(filter -m32 -m64, $(KBUILD_CFLAGS))
-endif
+userldflags += -static
 
 $(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh