FindFirstEx and FindFirst on Linux cannot find anything with '*_' wildcard

[MissingNoGuy55]

On Linux, there seems to be an issue related to wildcards and finding files in general.

The following code will always fail on Linux, even with GAME set:

FileFindHandle_t hTest = FILESYSTEM_INVALID_FIND_HANDLE;
const char* pszTest = filesystem->FindFirstEx( "*_dir.vpk", "MOD", &hTest );

Msg("Wildcard test: %s\n", pszTest );

However, omitting the _ in the wildcard will make it work. This is not a problem on Windows it seems. Tested on Debian 12 and 13.

This also happens on EndeavourOS from my testing