allow mkfwimage to fail during atheros builds. sometimes images get too big for devices that use this image format, but this must not break the normal image build for other atheros devices

SVN-Revision: 11934

target/linux/atheros/image/Makefile

@@ -23,11 +23,11 @@ define Image/Build
 	$(call Image/Build/$(1))
 	dd if=$(KDIR)/root.$(1) of=$(BIN_DIR)/openwrt-$(BOARD)-root.$(1) bs=128k conv=sync
 
-	$(STAGING_DIR_HOST)/bin/mkfwimage -k $(BIN_DIR)/openwrt-$(BOARD)-vmlinux.lzma \
+	-$(STAGING_DIR_HOST)/bin/mkfwimage -k $(BIN_DIR)/openwrt-$(BOARD)-vmlinux.lzma \
 		-r $(BIN_DIR)/openwrt-$(BOARD)-root.$(1) \
 		-v XS2.ar2316.OpenWRT \
 		-o $(BIN_DIR)/openwrt-$(BOARD)-ubnt2-$(1).bin
-	$(STAGING_DIR_HOST)/bin/mkfwimage -k $(BIN_DIR)/openwrt-$(BOARD)-vmlinux.lzma \
+	-$(STAGING_DIR_HOST)/bin/mkfwimage -k $(BIN_DIR)/openwrt-$(BOARD)-vmlinux.lzma \
 		-r $(BIN_DIR)/openwrt-$(BOARD)-root.$(1) \
 		-v XS5.ar2313.OpenWRT \
 		-o $(BIN_DIR)/openwrt-$(BOARD)-ubnt5-$(1).bin \