stage2 大量优化代码使其自举编译时间大幅缩短

stage2/intrin.spl

@@ -161,10 +161,7 @@ fn table_count(): usize {
 
 fn strip_at(name: ByteView): ByteView {
     if name.len > 0 && name.ptr[0] == '@' {
-        match ByteView.slice(name, 1, name.len) {
-            .Ok(rest) => { ret rest; },
-            .Err(error) => { ret name; },
-        }
+        ret ByteView { .ptr = name.ptr + 1, .len = name.len - 1 };
     }
     ret name;
 }