Don't add duplicate lang

Don't add duplicate lang from FC_LANG if the pattern already has.

https://bugs.freedesktop.org/show_bug.cgi?id=81186
Symlinks fix for DESTDIR

From:
https://github.com/Alexpux/MINGW-packages/blob/master/mingw-w64-fontconfig/fontconfig-2.11.0-symlinks-fix.patch