Update expected test output.

Author: m-ou-se

src/test/ui/consts/const-eval/feature-gate-const_panic.stderr

@@ -9,20 +9,20 @@ LL | const Z: () = panic!("cheese");
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0658]: panicking in constants is unstable
-  --> $DIR/feature-gate-const_panic.rs:9:15
+  --> $DIR/feature-gate-const_panic.rs:6:15
    |
-LL | const X: () = unimplemented!();
-   |               ^^^^^^^^^^^^^^^^
+LL | const Y: () = unreachable!();
+   |               ^^^^^^^^^^^^^^
    |
    = note: see issue #51999 <https://github.com/rust-lang/rust/issues/51999> for more information
    = help: add `#![feature(const_panic)]` to the crate attributes to enable
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error[E0658]: panicking in constants is unstable
-  --> $DIR/feature-gate-const_panic.rs:6:15
+  --> $DIR/feature-gate-const_panic.rs:9:15
    |
-LL | const Y: () = unreachable!();
-   |               ^^^^^^^^^^^^^^
+LL | const X: () = unimplemented!();
+   |               ^^^^^^^^^^^^^^^^
    |
    = note: see issue #51999 <https://github.com/rust-lang/rust/issues/51999> for more information
    = help: add `#![feature(const_panic)]` to the crate attributes to enable

src/test/ui/consts/const-eval/unwind-abort.stderr

@@ -5,7 +5,7 @@ LL |     panic!()
    |     ^^^^^^^^
    |     |
    |     the evaluated program panicked at 'explicit panic', $DIR/unwind-abort.rs:5:5
-   |     inside `foo` at $SRC_DIR/std/src/macros.rs:LL:COL
+   |     inside `foo` at $SRC_DIR/std/src/panic.rs:LL:COL
    |     inside `_` at $DIR/unwind-abort.rs:8:15
 ...
 LL | const _: () = foo();

src/test/ui/consts/const-unwrap.stderr

@@ -5,7 +5,7 @@ LL |             None => panic!("called `Option::unwrap()` on a `None` value"),
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |                     |
    |                     the evaluated program panicked at 'called `Option::unwrap()` on a `None` value', $DIR/const-unwrap.rs:9:38
-   |                     inside `Option::<i32>::unwrap` at $SRC_DIR/core/src/macros/mod.rs:LL:COL
+   |                     inside `Option::<i32>::unwrap` at $SRC_DIR/core/src/panic.rs:LL:COL
    |                     inside `BAR` at $DIR/const-unwrap.rs:9:18
    | 
   ::: $DIR/const-unwrap.rs:9:1