contrib/loaders: Enforce Little Endian ARM machine code

arm-none-eabi target triplet defaults to Little Endian, and so far any
submitted machine code snippets have been verified to be Little Endian.
However a user might override [ARM_]CROSS_COMPILE with an armeb toolchain,
potentially resulting in invalid machine code.

Let's be safe and enforce Little Endian mode for assembler and compiler.

Change-Id: I9cefe24689eaded25d60ffb1f254b254e8d76f9d
Signed-off-by: Andreas Färber <afaerber@suse.de>
Reviewed-on: http://openocd.zylin.com/3498
Tested-by: jenkins
Reviewed-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>

contrib/loaders/flash/fm4/Makefile

@@ -6,6 +6,8 @@ CC=$(CROSS_COMPILE)gcc
 OBJCOPY=$(CROSS_COMPILE)objcopy
 OBJDUMP=$(CROSS_COMPILE)objdump
 
+CFLAGS = -static -nostartfiles -mlittle-endian -Wa,-EL
+
 all: erase.inc write.inc
 
 .PHONY: clean
@@ -15,7 +17,7 @@ all: erase.inc write.inc
 erase.elf write.elf: fm4.h
 
 %.elf: %.S
-	$(CC) -static -nostartfiles $< -o $@
+	$(CC) $(CFLAGS) $< -o $@
 
 %.lst: %.elf
 	$(OBJDUMP) -S $< > $@