Test that linking using the debug keyword to tll works.

Tests/CMakeCommands/target_link_libraries/CMakeLists.txt

@@ -114,3 +114,11 @@ endif()
 # shortcutting of the evaluation by returning an empty string.
 set(_exe_test $<STREQUAL:$<TARGET_PROPERTY:TYPE>,EXECUTABLE>)
 target_link_libraries(targetC $<$<AND:${_exe_test},${_exe_test}>:depG>)
+
+add_library(libConsumer empty.cpp)
+# This line causes $<$<CONFIG:Debug>:depA> to be used when
+# determining the include directories for libConsumer based on the
+# interface properties of its LINK_LIBRARIES. Because the above expression
+# evaluates to the empty string in non-Debug cases, ensure that that causes
+# no problems.
+target_link_libraries(libConsumer debug depA)