Comment 0 for bug 1033216

-Wundef will warn about the following lines:
/home/arch/widelands/src/i18n.cc:31:5: warning: "__APPLE__" is not defined [-Wundef]
/home/arch/widelands/src/i18n.cc:34:7: warning: "_WIN32" is not defined [-Wundef]
/home/arch/widelands/src/wlapplication.cc:919:7: warning: "WIN32" is not defined [-Wundef]
/home/arch/widelands/src/wlapplication.cc:981:7: warning: "WIN32" is not defined [-Wundef]
/home/arch/widelands/src/wlapplication.cc:983:7: warning: "__APPLE__" is not defined [-Wundef]
/home/arch/widelands/src/wlapplication.cc:1624:5: warning: "WIN32" is not defined [-Wundef]

From checking a few, I guess it doesn't like that these lines use #if instead of #ifdef.

If we do decide to change these, we should probably coordinate it so that we can get people on the platforms in question to test whether things still work as intended afterwards.