build cross gcc for ppc-linux

[Harry Lin]

On host : i686-pc-linux-gnu (Redhat 7.1)
to build powerpc-linux-gnu cross gcc 3.0.4, with binutils 2.12
./configure --target=powerpc-ibm-linux-gnu --with-newlib

seeing errors of files not exist while compiling in rs6000/linux.h about 
<signal.h> and <sys/ucontext.h>, while there are such files right there under 
/usr/include.

searching the archieves of gcc mailing lists, there were reports of such 
problems, but no one posted answers

although i can get into rs6000/linux.h to try to hack around, i bet this is a 
problem that must have been fixed gracefully,

any one knows sth about this....Thanx

Harry