/usr/src/linux-source-4.4.0/debian/scripts/link-headers is in linux-source-4.4.0 4.4.0-101.124.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42  | #!/bin/bash -e
. debian/debian.env
hdrdir="$1"
symdir="$2"
flavour="$3"
echo "Symlinking and copying headers for $flavour..."
excludes="( -path ./debian -prune -o -path ./${DEBIAN} -prune -o -path ./.git ) -prune -o"
(
find . $excludes  -type f \
	\( -name 'Makefile*' -o -name 'Kconfig*' -o -name 'Kbuild*' -o \
	-name '*.sh' -o -name '*.pl' -o -name '*.lds' \) -print
find ./include ./scripts -name .gitignore -prune -o -type f -print
find ./include -mindepth 1 -maxdepth 1 $excludes -type d -print
) | (
while read file; do
	dir=$file
	lastdir=$file
	if [ -e "$hdrdir/$file" -o -L "$hdrdir/$file" ]; then
		continue
	fi
	while [ ! -e "$hdrdir/$dir" -a ! -L "$hdrdir/$dir" ]; do
		lastdir=$dir
		dir=`dirname $dir`
	done
	# If the last item to exist is a symlink we assume all is good
	if [ ! -L "$hdrdir/$dir" ]; then
		# Turns things like "./foo" into "../"
		deref="`echo -n $lastdir | sed -e 's/^\.//' -e's,/[^/]*,../,g'`"
		item="`echo -n $lastdir | sed -e 's/^\.\///'`"
		ln -s $deref$symdir/$item $hdrdir/$item
	fi
done
)
exit
 |