I finally fixed the problem I had yesterday with autoconf and automake. I downgraded autoconf to the version from Mandrake 9.0, which is 2.53, and autoconf to 1.6.3. Now everything seems to work.

So, in summary, for Mandrake 9.1, I can compile KDE apps using automake1.6-1.6.3 and autoconf2.5-2.53.