oops, should have looked, bug 82601 is already open (says sparc only, though) and that it is probably due to some other lib, not mkfontdir code itself.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=82601 They point out that this: required from libc.so.6: 0x0d696911 0x00 05 GLIBC_2.1 0x0d696912 0x00 03 GLIBC_2.2 0x0d696910 0x00 02 GLIBC_2.0 (from objdump) is somewhat odd, and probably wrong...
