Seems like this plugin changes the rules ever so often. This is what worked for me today.
Remove old plugins from ~/.gimp2.8/plug-ins/
Get the latest code from https://github.com/bootchk/resynthesizer.git
git clone https://github.com/bootchk/resynthesizer.git
Install dependencies and compile code. ./configure doesn’t work as suggested, so I just ran the .autogen script, which did.
sudo apt install libglib2.0-dev libgimp2.0-dev automake intltool
sudo make install
# plugins went into here
Now when you start up gimp, you can see the Filters > Map > Resynthesize menu item, but I didn’t have the all-important Enhance > Heal Selection entry. That was got by installing another gimp package.
apt install gimp-plugin-registry # works on Ubuntu 18.04
apt install gimp-python # apparently works on 18.10 (with gimp 2.10)