Fixed the previous commit on Linux: The older GCC we are using

on our Debian build server does not support C++11 <codecvt>,
so the utf8 to utf16 conversion was replaced with Boost counterparts.

xs/src/slic3r/Utils/ASCIIFolding.hpp

@@ -7,6 +7,7 @@ namespace Slic3r {
 
 // If possible, remove accents from accented latin characters.
 // This function is useful for generating file names to be processed by legacy firmwares.
+extern std::string fold_utf8_to_ascii(const char *src);
 extern std::string fold_utf8_to_ascii(const std::string &src);
 
 }; // namespace Slic3r