revert CMakeList.txt change

Author: dietmarkuehl

tests/beman/execution26/CMakeLists.txt

@@ -129,7 +129,7 @@ foreach(test ${execution_tests})
   add_test(NAME ${TEST_EXE} COMMAND $<TARGET_FILE:${TEST_EXE}>)
 endforeach()
 
-if(PROJECT_IS_TOP_LEVEL)
+if(NOT PROJECT_IS_TOP_LEVEL)
   # test if the targets are findable from the build directory
   # cmake-format: off
   add_test(NAME find-package-test