Resolve #74419 (comment)

Author: Lokathor

src/librustc_target/spec/thumbv4t_nintendo_gba.rs

@@ -65,9 +65,6 @@ pub fn target() -> TargetResult {
             // The minimum alignment for global symbols.
             min_global_align: Some(4),
 
-            // no threads here
-            singlethread: true,
-
             // GBA has no builtins
             no_builtins: true,