libretro: add VFS implementation

[cscd98]

This is experimental, and is disabled by default. I recommend backing up any save games because a couple of times I've had a system error with corrupt saves, however not recently.

There is a new option under Core Options->RetroArch > Enable Virtual File System (VFS)

Tested under local files and SMB shares.

This requires a retroarch nightly, or at at least RetroArch > 1.22.2

Tested on Linux & Android.

Fixes: #391

[i30817]

This will likely also fix SAF access for sdcards and RSAF rclone backends (WebDAV etc) access in android, or at least libretro vfs with the right replacements is the only requirement in the core.

I'm pretty sure that SAF "accidentally" works on a bunch of cores that had vfs for Xbox before saf paths got merged in retroarch and worked immediately after.

[i30817]

Still being worked on, or just rebased?

[cscd98]

It just needs testing with a retroarch nightly.

[i30817]

Congratulations. One more core on the VFS throne. So useful for android.

[i30817]

Hey @cscd98 , I just tried this now and while I can load WiiWare/wad files, I can't load m3u files with rvzs

I think it might be the same problem that @LibretroAdmin fixed after I reported it in discord for beetle and others, of the libchd library loading the file with fopen directly only for m3u. I'll post this also in the discord so he can see it if the @ doesn't work

[i30817]

Ok weird

The core info file says it does support m3u.

Which means either its wrong, or m3u aren't loading correctly over vfs. (The wiki doesn't list m3u at https://docs.libretro.com/library/dolphin/#extensions )

Rvz actually load fine.

Here is where m3u is loaded:

https://github.com/libretro/dolphin/blob/master/Source%2FCore%2FCore%2FBoot%2FBoot.cpp#L67