Fix incorrect scaling for SaveXmm128Far.

The `SaveXmm128Far` unwind op should have a 32-bit unscaled value.

The value was accidentally scaled down by 16 while calculating whether or not
the `SaveXmm128` or `SaveXmm128Far` unwind op should be used.

cranelift/codegen/src/isa/unwind/winx64.rs

@@ -80,13 +80,13 @@ impl UnwindCode {
                 stack_offset,
             } => {
                 writer.write_u8(*offset);
-                let stack_offset = stack_offset / 16;
-                if stack_offset <= core::u16::MAX as u32 {
+                let scaled_stack_offset = stack_offset / 16;
+                if scaled_stack_offset <= core::u16::MAX as u32 {
                     writer.write_u8((*reg << 4) | (UnwindOperation::SaveXmm128 as u8));
-                    writer.write_u16::<LittleEndian>(stack_offset as u16);
+                    writer.write_u16::<LittleEndian>(scaled_stack_offset as u16);
                 } else {
                     writer.write_u8((*reg << 4) | (UnwindOperation::SaveXmm128Far as u8));
-                    writer.write_u16::<LittleEndian>(stack_offset as u16);
+                    writer.write_u16::<LittleEndian>(*stack_offset as u16);
                     writer.write_u16::<LittleEndian>((stack_offset >> 16) as u16);
                 }
             }