Rollup merge of #70540 - jonas-schievink:link-attr-template, r=varkor

#[link]: mention wasm_import_module instead of cfg

`#[link(cfg)]` is perma-unstable and is not documented anywhere else. It makes more sense to mention `wasm_import_module` here since it's stable.

This makes it harder to hit #70538 (if it weren't for this text, I wouldn't even know this feature existed).

Author: Dylan-DPC

src/librustc_feature/builtin_attrs.rs

@@ -220,7 +220,7 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     // ABI, linking, symbols, and FFI
     ungated!(
         link, Whitelisted,
-        template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ cfg = "...""#),
+        template!(List: r#"name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...""#),
     ),
     ungated!(link_name, Whitelisted, template!(NameValueStr: "name")),
     ungated!(no_link, Normal, template!(Word)),

src/test/ui/malformed/malformed-regressions.stderr

@@ -26,7 +26,7 @@ LL | #[inline = ""]
    = 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 #57571 <https://github.com/rust-lang/rust/issues/57571>
 
-error: attribute must be of the form `#[link(name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ cfg = "...")]`
+error: attribute must be of the form `#[link(name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...")]`
   --> $DIR/malformed-regressions.rs:7:1
    |
 LL | #[link]
@@ -35,7 +35,7 @@ LL | #[link]
    = 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 #57571 <https://github.com/rust-lang/rust/issues/57571>
 
-error: attribute must be of the form `#[link(name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ cfg = "...")]`
+error: attribute must be of the form `#[link(name = "...", /*opt*/ kind = "dylib|static|...", /*opt*/ wasm_import_module = "...")]`
   --> $DIR/malformed-regressions.rs:9:1
    |
 LL | #[link = ""]