Fix test failures due to normalization

Author: LeSeulArtichaut

src/test/ui/consts/miri_unleashed/mutable_const2.stderr

@@ -10,7 +10,7 @@ error: internal compiler error: mutable allocation in constant
 LL | const MUTABLE_BEHIND_RAW: *mut i32 = &UnsafeCell::new(42) as *const _ as *mut _;
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', src/librustc_errors/lib.rs:355:17
+thread 'rustc' panicked at 'no errors encountered even though `delay_span_bug` issued', $SRC_DIR/librustc_errors/lib.rs:LL:COL
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
 error: internal compiler error: unexpected panic

src/test/ui/consts/miri_unleashed/mutable_references_ice.stderr

@@ -6,7 +6,7 @@ LL |     x: &UnsafeCell::new(42),
 
 thread 'rustc' panicked at 'assertion failed: `(left != right)`
   left: `Const`,
- right: `Const`: UnsafeCells are not allowed behind references in constants. This should have been prevented statically by const qualification. If this were allowed one would be able to change a constant at one use site and other use sites could observe that mutation.', src/librustc_mir/interpret/intern.rs:LL:CC
+ right: `Const`: UnsafeCells are not allowed behind references in constants. This should have been prevented statically by const qualification. If this were allowed one would be able to change a constant at one use site and other use sites could observe that mutation.', $SRC_DIR/librustc_mir/interpret/intern.rs:LL:COL
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
 error: internal compiler error: unexpected panic

src/test/ui/pattern/const-pat-ice.stderr

@@ -1,4 +1,4 @@
-thread 'rustc' panicked at 'assertion failed: rows.iter().all(|r| r.len() == v.len())', src/librustc_mir_build/hair/pattern/_match.rs:LL:CC
+thread 'rustc' panicked at 'assertion failed: rows.iter().all(|r| r.len() == v.len())', $SRC_DIR/librustc_mir_build/hair/pattern/_match.rs:LL:COL
 note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
 
 error: internal compiler error: unexpected panic