Run no_core rustdoc tests on Linux only.

Windows on Macos ARM64 produce linker errors.

Author: hkratz

src/test/rustdoc/cross-crate-primitive-doc.rs

@@ -1,6 +1,6 @@
 // aux-build:primitive-doc.rs
 // compile-flags: --extern-html-root-url=primitive_doc=../ -Z unstable-options
-// ignore-windows
+// only-linux
 
 #![feature(no_core)]
 #![no_core]

src/test/rustdoc/intra-doc/prim-methods-external-core.rs

@@ -1,7 +1,7 @@
 // aux-build:my-core.rs
 // build-aux-docs
 // ignore-cross-compile
-// ignore-windows
+// only-linux
 
 #![deny(broken_intra_doc_links)]
 #![feature(no_core, lang_items)]