[klibc] __builtin_clz in klibc

[Heiko Carstens]

Hi,

I just got a bug report that klibc doesn't compile on s390:

  KLIBCCC usr/klibc/libgcc/__clzsi2.o
  KLIBCCC usr/klibc/libgcc/__clzdi2.o
usr/klibc/libgcc/__clzdi2.c: In function `__clzdi2':
usr/klibc/libgcc/__clzdi2.c:24: warning: implicit declaration of function `__builtin_clz'

This looks like a common problem, because __builtin_clz is available since
gcc 3.4, while the kernel should compile even with gcc 3.2.
Looks like counting the zero bits should be done differently...