Fix binary architectures.

Makefile

@@ -8,7 +8,6 @@ run: image.bin
 debug-boot: image.bin mbr.elf
 	qemu-system-i386 -drive format=raw,file=$< -s -S &
 	x86_64-elf-gdb mbr.elf \
-		-ex "set architecture i386" \
 		-ex "target remote localhost:1234" \
 		-ex "break init_32bit" \
 		-ex "continue"
@@ -30,13 +29,13 @@ kernel.bin: kernel.o vga.o string.o drivers/ata.o
 	$(CC) -m32 -ffreestanding -c -g $< -o $@
 
 %.o: %.S
-	$(AS) $^ -g -o $@
+	$(CC) -m32 $^ -c -g -o $@
 
 mbr.bin: mbr.o
-	$(LD) -Ttext=0x7c00 --oformat=binary $^ -o $@
+	$(LD) -m elf_i386 -Ttext=0x7c00 --oformat=binary $^ -o $@
 
 mbr.elf: mbr.o
-	$(LD) -Ttext=0x7c00 $^ -o $@
+	$(LD) -m elf_i386 -Ttext=0x7c00 $^ -o $@
 
 clean:
-	rm *.bin *.o
+	rm -f *.bin *.o