Rollup merge of rust-lang#131379 - ehuss:fix-utf8-bom, r=jieyouxu

Fix utf8-bom test

The BOM was accidentally removed in rust-lang#57108

I had to move the run-pass line down, because compiletest doesn't seem to know about BOMs, so it does not parse the header if it is the first line.

Author: Zalathar

tests/ui/utf8-bom.rs

@@ -1,6 +1,4 @@
+// This file has utf-8 BOM, it should be compiled normally without error.
 //@ run-pass
-//
-
-// This file has utf-8 BOM, it should be compiled normally without error.
 
 pub fn main() {}