test: Let Autoconf generate env vars for tests

This simplifies the setup script a lot, and also makes it easier to
run tests independently.

Signed-off-by: Jacques de Laval <jacques@de-laval.se>

test/checkself.sh

@@ -5,4 +5,4 @@ set -eu
 testdir="${srcdir:-$(dirname "$0")}"
 
 # shellcheck disable=SC2046
-shellcheck $(find "$testdir" -name '*.sh')
+shellcheck $(find "$testdir" -path "$testdir/test-root" -prune -false -o -name '*.sh')