need to remove any libiberty.a from toolchain build

package/binutils/Makefile

@@ -39,8 +39,8 @@ CONFIGURE_ARGS+=	--disable-werror \
 # disable honour cflags stuff
 XAKE_FLAGS+=		GCC_HONOUR_COPTS=s
 
-post-build:
-	$(CP) ${WRKBUILD}/libiberty/libiberty.a $(STAGING_TARGET_DIR)/usr/lib
+pre-build:
+	@-rm $(STAGING_TARGET_DIR)/usr/lib/libiberty.a
 
 libbfd-install:
 	${INSTALL_DIR} ${IDIR_LIBBFD}/usr/lib