Don't shutdown termbox2 if authentication fails

Signed-off-by: AnErrupTion <anerruption@disroot.org>

src/auth.zig

@@ -20,6 +20,7 @@ pub const AuthOptions = struct {
     setup_cmd: []const u8,
     login_cmd: ?[]const u8,
     x_cmd: []const u8,
+    session_pid: std.posix.pid_t,
 };
 
 var xorg_pid: std.posix.pid_t = 0;
@@ -164,6 +165,9 @@ fn startSession(
     // Change to the user's home directory
     std.posix.chdirZ(pwd.pw_dir.?) catch return error.ChangeDirectoryFailed;
 
+    // Signal to the session process to give up control on the TTY
+    _ = std.posix.kill(options.session_pid, std.posix.SIG.CHLD) catch return error.TtyControlTransferFailed;
+
     // Execute what the user requested
     switch (current_environment.display_server) {
         .wayland => try executeWaylandCmd(pwd.pw_shell.?, options, current_environment.cmd),