unset executable bit on firmware image

This firmware is not meant to be executed on the host machine, so
unset its executable bit.  Noticed by lintian.

While at it, teach stage1 builds to recover from interrupted builds by
ensuring *stage1.bin are not present until all of the relevant
commands have been run.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

usbboot/xburst_stage1/Makefile

@@ -23,10 +23,12 @@ OBJS	= head.o main.o common.o board_4740.o board_4750.o debug.o
 all: xburst_stage1.bin
 
 xburst_stage1.bin: xburst_stage1.elf
-	$(CROSS_COMPILE)objcopy -O binary $< $@
+	$(CROSS_COMPILE)objcopy -O binary $< $@+
 	$(CROSS_COMPILE)objdump -D $< > xburst_stage1.dump
 	$(CROSS_COMPILE)objdump -h $< > xburst_stage1.map
 	$(CROSS_COMPILE)nm -n $< > System.map
+	chmod -x $@+
+	mv -f $@+ $@
 
 xburst_stage1.elf: $(OBJS)
 	$(CROSS_COMPILE)ld $(LDFLAGS) $(OBJS) -o $@

usbboot/xburst_stage2/Makefile

@@ -37,6 +37,7 @@ OBJS	= main.o udc.o cache.o serial.o boothandler.o nandflash_4740.o nandflash_47
 
 all: xburst_stage2.elf
 	$(OBJCOPY) -O binary xburst_stage2.elf xburst_stage2.bin
+	chmod -x xburst_stage2.bin
 	$(OBJDUMP) -D xburst_stage2.elf > xburst_stage2.dump
 	$(NM) xburst_stage2.elf | sort > xburst_stage2.sym
 	$(OBJDUMP) -h xburst_stage2.elf > xburst_stage2.map

xbboot/target-stage1/Makefile

@@ -21,10 +21,12 @@ OBJS	= head.o stage1.o serial.o
 all: stage1.bin
 
 stage1.bin: stage1.elf
-	$(CROSS_COMPILE)objcopy -O binary $< $@
+	$(CROSS_COMPILE)objcopy -O binary $< $@+
 	$(CROSS_COMPILE)objdump -D $< > stage1.dump
 	$(CROSS_COMPILE)objdump -h $< > stage1.map
 	$(CROSS_COMPILE)nm -n $< > System.map
+	chmod -x $@+
+	mv -f $@+ $@
 
 stage1.elf: $(OBJS)
 	$(CROSS_COMPILE)ld $(LDFLAGS) $(OBJS) -o $@