It should *not* be in /lib, it belongs in /usr/lib.. /lib is for system-dependant libs required for starting up the system. Get rid of the symlink in /lib and make sure the actual binary lib is in /usr/lib, and make sure you have read permissions for it.
i tryed ./eggdrop -v with root rights so it should have all rights...
/usr/lib/libtcl8.4.so
its there....
EDIT//
checking for Tcl library... found /usr/local/lib/libtcl8.4.so
checking for Tcl header... found /usr/local/include/tcl.h
the compile found the lib but the eggdrop doesnt find...
Test run of ./eggdrop -v:
./eggdrop: error while loading shared libraries: libtcl8.4.so: cannot open shared object file: No such file or directory
make: *** [modules] Error 127