Rollup merge of rust-lang#145464 - Kivooeo:stabilize-const_pathbuf_osstring_new, r=ibraheemdev

Stabilize `const_pathbuf_osstring_new` feature

This closes [tracking issue](rust-lang#141520) and stabilises `{OsString, PathBuf}::new` in const

Author: jieyouxu

std/src/ffi/os_str.rs

@@ -137,7 +137,7 @@ impl OsString {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[inline]
-    #[rustc_const_unstable(feature = "const_pathbuf_osstring_new", issue = "141520")]
+    #[rustc_const_stable(feature = "const_pathbuf_osstring_new", since = "CURRENT_RUSTC_VERSION")]
     pub const fn new() -> OsString {
         OsString { inner: Buf::from_string(String::new()) }
     }

std/src/path.rs

@@ -1191,7 +1191,7 @@ impl PathBuf {
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use]
     #[inline]
-    #[rustc_const_unstable(feature = "const_pathbuf_osstring_new", issue = "141520")]
+    #[rustc_const_stable(feature = "const_pathbuf_osstring_new", since = "CURRENT_RUSTC_VERSION")]
     pub const fn new() -> PathBuf {
         PathBuf { inner: OsString::new() }
     }