编译busybox出现问题

我的GCC是4.3.3的 busybox 是1.13.0的  编译的时候出现 下面这些错误 不知道 怎么回事呢

C      libbb/time.o
libbb/time.c: In function `get_mono':
libbb/time.c:25: `__NR_clock_gettime' undeclared (first use in this function)
libbb/time.c:25: (Each undeclared identifier is reported only once
libbb/time.c:25: for each function it appears in.)
make[1]: *** [libbb/time.o] Error 1
make: *** [libbb] Error 2
  CC      libbb/time.o
libbb/time.c: In function `get_mono':
libbb/time.c:25: `__NR_clock_gettime' undeclared (first use in this function)
libbb/time.c:25: (Each undeclared identifier is reported only once
libbb/time.c:25: for each function it appears in.)
make[1]: *** [libbb/time.o] Error 1
make: *** [libbb] Error 2

建议用光盘的交叉编译器和busybox，编译没问题的。