Fix stability and deprecation markers on soft_link and symlink

The change to split up soft_link to OS-specific symlink, symlink_file,
and symlink_dir didn't actually land in 1.0.0.  Update the stability and
deprecation attributes to correctly indicate that these changes happend
in 1.1.0.

src/libstd/sys/unix/ext/fs.rs

@@ -184,7 +184,7 @@ impl DirEntryExt for fs::DirEntry {
 /// # Ok(())
 /// # }
 /// ```
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "symlink", since = "1.1.0")]
 pub fn symlink<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q) -> io::Result<()>
 {
     sys::fs::symlink(src.as_ref(), dst.as_ref())

src/libstd/sys/windows/ext/fs.rs

@@ -122,7 +122,7 @@ impl MetadataExt for Metadata {
 /// # Ok(())
 /// # }
 /// ```
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "symlink", since = "1.1.0")]
 pub fn symlink_file<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q)
                                                     -> io::Result<()> {
     sys::fs::symlink_inner(src.as_ref(), dst.as_ref(), false)
@@ -143,7 +143,7 @@ pub fn symlink_file<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q)
 /// # Ok(())
 /// # }
 /// ```
-#[stable(feature = "rust1", since = "1.0.0")]
+#[stable(feature = "symlink", since = "1.1.0")]
 pub fn symlink_dir<P: AsRef<Path>, Q: AsRef<Path>>(src: P, dst: Q)
                                                    -> io::Result<()> {
     sys::fs::symlink_inner(src.as_ref(), dst.as_ref(), true)