AvlTree-tests: executable not found

cc fyi @Bodigrim: probably a common stackage build env issue

Author: juhp

build-constraints.yaml

@@ -8135,6 +8135,9 @@ expected-test-failures:
     - functor-combinators # 0.4.1.4 https://github.com/mstksg/functor-combinators/issues/9
     - path # 0.9.6 https://github.com/commercialhaskell/stackage/issues/7503
 
+    # executable not found in our environment
+    - AvlTree # 4.3: AvlTree-tests:  executable not found
+
     # Consistent test failures
     - Allure # 0.11.0.0
     - ANum # executable not found, https://github.com/commercialhaskell/stackage/issues/7809