build: add workaround for CMake

It seems that `RPATH` is not properly handled by CMake on executables.
Restore the old workaround for the time being.

Author: compnerd

Tests/Tools/XDGTestHelper/CMakeLists.txt

@@ -6,3 +6,7 @@ target_link_libraries(xdgTestHelper PRIVATE
   FoundationXML)
 set_target_properties(xdgTestHelper PROPERTIES
   BUILD_RPATH "$<TARGET_FILE_DIR:swiftDispatch>;$<TARGET_FILE_DIR:Foundation>;$<TARGET_FILE_DIR:FoundationNetworking>;$<TARGET_FILE_DIR:FoundationXML>")
+if(NOT CMAKE_SYSTEM_NAME STREQUAL Windows)
+  target_link_options(xdgTestHelper PRIVATE
+    "SHELL:-Xlinker -rpath -Xlinker $<TARGET_FILE_DIR:swiftDispatch>:$<TARGET_FILE_DIR:Foundation>:$<TARGET_FILE_DIR:FoundationNetworking>:$<TARGET_FILE_DIR:FoundationXML>")
+endif()