h8300: suppress error messages for 'make clean'

'make ARCH=h8300 clean' emits error messages as follows:

  $ make ARCH=h8300 clean
  gcc: error: missing argument to '-Wframe-larger-than='
  gcc: error: unrecognized command line option '-mint32'

You can suppress the second one by setting the correct CROSS_COMPILE=,
but we should not require any compiler for cleaning.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

arch/h8300/boot/compressed/Makefile

@@ -18,7 +18,7 @@ CONFIG_MEMORY_START     ?= 0x00400000
 CONFIG_BOOT_LINK_OFFSET ?= 0x00280000
 IMAGE_OFFSET := $(shell printf "0x%08x" $$(($(CONFIG_MEMORY_START)+$(CONFIG_BOOT_LINK_OFFSET))))
 
-LIBGCC := $(shell $(CROSS-COMPILE)$(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name)
+LIBGCC := $(shell $(CROSS-COMPILE)$(CC) $(KBUILD_CFLAGS) -print-libgcc-file-name 2>/dev/null)
 LDFLAGS_vmlinux := -Ttext $(IMAGE_OFFSET) -estartup -T $(obj)/vmlinux.lds \
 	--defsym output=$(CONFIG_MEMORY_START)