Bug#1102644: luanti FTCBFS: fails creating /minetest

[Helmut Grohne]

Source: luanti
Version: 5.10.0+dfsg-3
Tags: patch upstream
User: debian-cross at lists.debian.org
Usertags: ftcbfs

luanti fails to cross build from source, because it attempts to create
/minetest and that happens to not work resulting in Permission denied as
expected. The root cause for this is that EXECUTABLE_OUTPUT_PATH ends up
being empty, because upstream thought that in a cross build setting it
should be empty. As much as I can relate to that, my appreciation for
the resulting build failure is fairly limited and I suggest discarding
that branch. Generally speaking, cross/native differences tend to be a
recipe for failure. Patch attached.

Helmut