[Makefile bug] make barebox.s : dead loop

[Kevin Du Huanpeng]

How to reproduce this:
1. edit Makefile
> 169 ARCH            ?= mips
> 170 CROSS_COMPILE   ?= mips-linux-gnu-
2. make some defconfig
> make dlink-dir-320_defconfig
3. make barebox.s
>make barebox.s
4. endless make....
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  LD      barebox
  SYSMAP  System.map
  DISASM  barebox.S
  CHK     include/generated/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/compile.h
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  AS      arch/mips/boot/start.o
  LD      arch/mips/boot/built-in.o
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      common/version.o
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  LD      barebox
  SYSMAP  System.map
  DISASM  barebox.S
  CHK     include/generated/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/compile.h
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  AS      arch/mips/boot/start.o
  LD      arch/mips/boot/built-in.o
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      common/version.o
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  LD      barebox
  SYSMAP  System.map
  DISASM  barebox.S
  CHK     include/generated/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/compile.h
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  AS      arch/mips/boot/start.o
  LD      arch/mips/boot/built-in.o
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      common/version.o
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  LD      barebox
  SYSMAP  System.map
  DISASM  barebox.S
  CHK     include/generated/version.h
  CHK     include/generated/utsrelease.h
  CHK     include/generated/compile.h
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  AS      arch/mips/boot/start.o
  LD      arch/mips/boot/built-in.o
  GEN     .version
  CHK     include/generated/compile.h
  UPD     include/generated/compile.h
  CC      common/version.o
  PWDH    include/generated/passwd.h
  CC      common/password.o
  LD      common/built-in.o
  LD      barebox
  SYSMAP  System.map
  DISASM  barebox.S
^Cmake[9]: *** wait: No child processes.  Stop.
make[9]: *** Waiting for unfinished jobs....
make[9]: *** wait: No child processes.  Stop.
make[8]: *** [barebox.s] Error 2
make[7]: *** [barebox.s] Interrupt
make[6]: *** [barebox.s] Interrupt
make[5]: *** [barebox.s] Interrupt
make[4]: *** [barebox.s] Interrupt
make[3]: *** [barebox.s] Interrupt
make[2]: *** [barebox.s] Interrupt
make[1]: *** [barebox.s] Interrupt
make: *** [barebox.s] Interrupt