Two changes here.
- Make the mount path follow server temp folder requirements.
- Will be mounted in `/tmp/` or `$XDG_RUNTIME_DIR/` now
- Switch the FEXServer socket to an "abstract" AF_UNIX socket.
- If the socket is in `/tmp/` then systemd will put the service in a
private `/tmp` folder that only exists for the service.
- If the socket is in `$XDG_RUNTIME_DIR` then pressure-vessel can't
chroot anymore since they make their own runtime directory.
- If it is in `$HOME/.fex-emu/` then it breaks usage where the
filesystem is a mount that doesn't support AF_UNIX like sshfs.
The only reasonable thing to do is to switch over to `abstract` sockets
which will work in all cases.
Tested with pressure-vessel and systemd and now it works in all
situations.
This is a relatively invasive change since multiple things needed to
happen at once.
* Socket based logging is removed
* Logging has been replaced to only support stdout, stderr, and server
* Server is now default and replaces what FEXLogServer did
* Server logging now uses a pipe instead of a socket
* Can be faster than stderr and stdout since the application doesn't
need to wait on terminal output
* FEXMountDaemon has been removed
* Functionality has been merged in to FEXServer
* FEXServer is always executed on FEX initialization time
* Similar in behaviour to Wine's wineserver
* Can explicitly start this before using FEX for logging purposes
* Stays around until all instances of FEX exit
* Will stick around for a short amount of time in case of spurious
execution
* FEXServer will soon be extended to do more than logging and squashfs
mounting
* FEX rootfs scripts will need to be updated to support this path
* Just means rbinding the /tmp folder and forcing a FEXServer instance
to be alive
* Pressure-vessel works fine in this case since FEXServer will already
be running
* It already rbinds the host /tmp folder which is why this works