try to manually bless windows test output

Author: RalfJung

tests/ui/linkage-attr/raw-dylib/windows/unsupported-abi.rs

@@ -3,6 +3,8 @@
 //@ compile-flags: --crate-type lib --emit link
 #[link(name = "foo", kind = "raw-dylib")]
 extern "stdcall" {
+//~^ WARN: calling convention not supported on this target
+//~| WARN: previously accepted
     fn f(x: i32);
     //~^ ERROR ABI not supported by `#[link(kind = "raw-dylib")]` on this architecture
 }

tests/ui/linkage-attr/raw-dylib/windows/unsupported-abi.stderr

@@ -1,8 +1,36 @@
+warning: use of calling convention not supported on this target
+  --> $DIR/unsupported-abi.rs:5:1
+   |
+LL | / extern "stdcall" {
+LL | |     fn f(x: i32);
+LL | |
+LL | | }
+   | |_^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #137018 <https://github.com/rust-lang/rust/issues/137018>
+   = help: if you need `extern "stdcall"` on win32 and `extern "C"` everywhere else, use `extern "system"`
+   = note: `#[warn(unsupported_calling_conventions)]` on by default
+
 error: ABI not supported by `#[link(kind = "raw-dylib")]` on this architecture
-  --> $DIR/unsupported-abi.rs:6:5
+  --> $DIR/unsupported-abi.rs:8:5
    |
 LL |     fn f(x: i32);
    |     ^^^^^^^^^^^^^
 
-error: aborting due to 1 previous error
+error: aborting due to 1 previous error; 1 warning emitted
 
+Future incompatibility report: Future breakage diagnostic:
+warning: use of calling convention not supported on this target
+  --> $DIR/unsupported-abi.rs:5:1
+   |
+LL | / extern "stdcall" {
+LL | |     fn f(x: i32);
+LL | |
+LL | | }
+   | |_^
+   |
+   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
+   = note: for more information, see issue #137018 <https://github.com/rust-lang/rust/issues/137018>
+   = help: if you need `extern "stdcall"` on win32 and `extern "C"` everywhere else, use `extern "system"`
+   = note: `#[warn(unsupported_calling_conventions)]` on by default