[PATCH 0/1] MR7901: ntdll: Treat XDG_DATA_DIRS as special env variable.

[Louis Lenders (＠xe)]

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=49987

GTK apps seem to use this env var to find path to schemas, like
Meld: https://download.gnome.org/binaries/win32/meld/3.22/Meld-3.22.2-mingw.msi
which doesn't start at all without this patch.
More info in https://bugs.winehq.org/show_bug.cgi?id=49987.

v2: add WINEXDG_DATA_DIRS and use that in winemenubuilder.