Comment # 2 on bug 1207959 from Reinhard Max

Not a bad guess, but that change is about the libraries that are being used to
link libtcl itself.

The problem here was that install-libraries-libdir.patch wasn't doing things
properly or not being applied at all. I changed the package to install
everything under %tcl_archdir (which expands to %_libdir/tcl), so that
pkgIndex.tcl and the shared object it loads are next to each other again.