Trouble in compiling kernel 2.4.20

[Charles Trois]

My machine is a new style iMac, running YDL 2.3. The kernel in use is
2.4.19.

As an exercise, I would like to get the most recent stable kernel, which
appears to be 2.4.20.

I therefore downloaded the proper source from kernel.org and tried to build
the kernel. After xconfig, I launched "make dep"; this is where things went
wrong, as shown by the last lines of the log:

make[1]: Leaving directory `/usr/src/linux-2.4.20/arch/ppc/boot'
scripts/mkdep -- init/*.c > .depend
scripts/mkdep -- `find /usr/src/linux-2.4.20/include/asm
/usr/src/linux-2.4.20/include/linux /usr/src/linux-2.4.20/include/scsi
/usr/src/linux-2.4.20/include/net /usr/src/linux-2.4.20/include/math-emu \(
-name SCCS -o -name .svn \) -prune -o -follow -name \*.h ! -name
modversions.h 
-print` > .hdepend
/bin/sh: scripts/mkdep: Argument list too long
make: *** [dep-files] Error 126

The same happened with other downloads (ppckernel.org, also the benh tree).