CMake: Set runtime plugins output directory even when the rest are not set

src/MagnumPlugins/CMakeLists.txt

@@ -33,10 +33,14 @@ macro(add_plugin plugin_name plugin_folder debug_install_dirs release_install_di
         corrade_add_static_plugin(${plugin_name} "${release_install_dirs}" ${metadata_file} ${ARGN})
         set_target_properties(${plugin_name} ${plugin_name}-dependencies PROPERTIES FOLDER "MagnumPlugins/${plugin_name}")
     endif()
-    # Modify output location only if all are set, otherwise it makes no sense
+    # Modify only runtime output location if that one is set
+    if(CMAKE_RUNTIME_OUTPUT_DIRECTORY)
+        set_target_properties(${plugin_name} PROPERTIES
+            RUNTIME_OUTPUT_DIRECTORY ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/magnum$<$<CONFIG:Debug>:-d>/${plugin_folder})
+    endif()
+    # Modify the other output locations if all are set
     if(CMAKE_RUNTIME_OUTPUT_DIRECTORY AND CMAKE_LIBRARY_OUTPUT_DIRECTORY AND CMAKE_ARCHIVE_OUTPUT_DIRECTORY)
         set_target_properties(${plugin_name} PROPERTIES
-            RUNTIME_OUTPUT_DIRECTORY ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}/magnum$<$<CONFIG:Debug>:-d>/${plugin_folder}
             LIBRARY_OUTPUT_DIRECTORY ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/magnum$<$<CONFIG:Debug>:-d>/${plugin_folder}
             ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_ARCHIVE_OUTPUT_DIRECTORY}/magnum$<$<CONFIG:Debug>:-d>/${plugin_folder})
     endif()