libstd: win: Don't expose link() on UWP

Author: chouquette

src/libstd/sys/windows/c.rs

@@ -1215,6 +1215,7 @@ extern "system" {
                      lpOverlapped: LPOVERLAPPED)
                      -> BOOL;
     pub fn CloseHandle(hObject: HANDLE) -> BOOL;
+    #[cfg(not(target_os = "uwp"))]
     pub fn CreateHardLinkW(lpSymlinkFileName: LPCWSTR,
                            lpTargetFileName: LPCWSTR,
                            lpSecurityAttributes: LPSECURITY_ATTRIBUTES)

src/libstd/sys/windows/fs.rs

@@ -710,6 +710,7 @@ pub fn symlink_inner(src: &Path, dst: &Path, dir: bool) -> io::Result<()> {
     Ok(())
 }
 
+#[cfg(not(target_os = "uwp"))]
 pub fn link(src: &Path, dst: &Path) -> io::Result<()> {
     let src = to_u16s(src)?;
     let dst = to_u16s(dst)?;
@@ -719,6 +720,12 @@ pub fn link(src: &Path, dst: &Path) -> io::Result<()> {
     Ok(())
 }
 
+#[cfg(target_os = "uwp")]
+pub fn link(_src: &Path, _dst: &Path) -> io::Result<()> {
+    return Err(io::Error::new(io::ErrorKind::Other,
+                            "hard link are not supported on UWP"));
+}
+
 pub fn stat(path: &Path) -> io::Result<FileAttr> {
     let mut opts = OpenOptions::new();
     // No read or write permissions are necessary