tclkit.exe is a single-file Tcl/Tk runtime. The one included in TeX
Live is generated with kitcreator. This program downloads and
compiles tcl, tk and various pieces of infrastructure.

I used kitcreator's README file for guidance in generating
tclkit.exe:

from the root of the unpacked kitcreator archive I first created a
native Linux tclkit:

./kitcreator
mv tclkit-8.6.8 tclkit-local

From this same directory I ran the following script:

================
#!/bin/bash
export TCLKIT=`pwd`/tclkit-local
export CROSS=i686-w64-mingw32

export CC=${CROSS}-gcc
export CXX=${CROSS}-c++
export AR=${CROSS}-ar
export RANLIB=${CROSS}-ranlib
export STRIP=${CROSS}-strip
export RC=${CROSS}-windres
./kitcreator --host=${CROSS}

mv tclkit-8.6.8 tclkit.exe
================

This directory contains the archives of kitcreator and the archives
it downloaded during the build process.

The LICENSE file is the one I found in the root of the kitcreator
archive.

As to the urls of the downloaded files: a command

find . -name "build*.sh" -exec grep '^SRCURL=' \{} \;

generated the following output:

SRCURL="http://sourceforge.net/projects/incrtcl/files/%5BIncr%20Tcl_Tk%5D-source/Itcl%20${ITCLVERS}/itcl${ITCLVERS}${ITCLVERSEXTRA}.tar.gz/download"
SRCURL="http://prdownloads.sourceforge.net/tcl/tcl${TCLVERS}-src.tar.gz"
SRCURL="http://sourceforge.net/projects/tcl/files/Thread%20Extension/${THREADVERS}/thread${THREADVERS}.tar.gz/download"
SRCURL="http://www.equi4.com/pub/mk/metakit-${MK4VERS}.tar.gz"
SRCURL="http://pkgs.fedoraproject.org/repo/pkgs/metakit/metakit-${MK4VERS}.tar.gz/17330257376eea657827ed632ea62c9e/metakit-${MK4VERS}.tar.gz"
SRCURL="http://prdownloads.sourceforge.net/tcl/tk${TCLVERS}-src.tar.gz"

The itcl- and thread- packages listed above were not actually downloaded.

Siep Kroonenberg
November 2018