Cygwin: unlink_nt: declare in winsup.h

unlink_nt is used more than once so declare it in a header.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/fhandler/disk_file.cc

@@ -1842,8 +1842,6 @@ fhandler_disk_file::mkdir (mode_t mode)
 int
 fhandler_disk_file::rmdir ()
 {
-  extern NTSTATUS unlink_nt (path_conv &pc, bool sharable);
-
   if (!pc.isdir ())
     {
       set_errno (ENOTDIR);

winsup/cygwin/forkable.cc

@@ -27,10 +27,6 @@ details. */
 #include <assert.h>
 #include <tls_pbuf.h>
 
-/* Allow concurrent processes to use the same dll or exe
- * via their hardlink while we delete our hardlink. */
-extern NTSTATUS unlink_nt (path_conv &pc, bool sharable);
-
 #define MUTEXSEP L"@"
 #define PATHSEP L"\\"
 

winsup/cygwin/local_includes/winsup.h

@@ -225,6 +225,8 @@ class path_conv;
 
 int stat_worker (path_conv &pc, struct stat *buf);
 
+NTSTATUS unlink_nt (path_conv &pc, bool sharable);
+
 ino_t readdir_get_ino (const char *path, bool dot_dot);
 
 /* mmap functions. */