configure: error:

  I can't find Tcl on this system.

  Eggdrop requires Tcl to compile.  If you already have Tcl installed
  on this system, and I just wasn't looking in the right place for it,
  set the environment variables TCLLIB and TCLINC so I will know where
  to find 'libtcl.a' (or 'libtcl.so') and 'tcl.h' (respectively). Then
  run 'configure' again.