Remove `shorten_filenames` (dead code)

src/path.c

@@ -1758,35 +1758,6 @@ char_u *shorten_fname(char_u *full_path, char_u *dir_name)
   return p;
 }
 
-#if (defined(FEAT_DND) && defined(FEAT_GUI_GTK)) \
-  || defined(FEAT_GUI_MSWIN) \
-  || defined(FEAT_GUI_MAC) \
-  || defined(PROTO)
-/*
- * Shorten all filenames in "fnames[count]" by current directory.
- */
-void shorten_filenames(char_u **fnames, int count)
-{
-  int i;
-  char_u dirname[MAXPATHL];
-  char_u      *p;
-
-  if (fnames == NULL || count < 1)
-    return;
-  os_dirname(dirname, sizeof(dirname));
-  for (i = 0; i < count; ++i) {
-    if ((p = shorten_fname(fnames[i], dirname)) != NULL) {
-      /* shorten_fname() returns pointer in given "fnames[i]".  If free
-       * "fnames[i]" first, "p" becomes invalid.  So we need to copy
-       * "p" first then free fnames[i]. */
-      p = vim_strsave(p);
-      vim_free(fnames[i]);
-      fnames[i] = p;
-    }
-  }
-}
-#endif
-
 /*
  * Invoke expand_wildcards() for one pattern.
  * Expand items like "%:h" before the expansion.

src/path.h

@@ -85,7 +85,6 @@ int pathcmp(const char *p, const char *q, int maxlen);
 int mch_expandpath(garray_T *gap, char_u *path, int flags);
 char_u *shorten_fname1(char_u *full_path);
 char_u *shorten_fname(char_u *full_path, char_u *dir_name);
-void shorten_filenames(char_u **fnames, int count);
 int expand_wildcards_eval(char_u **pat, int *num_file, char_u ***file,
                           int flags);
 int expand_wildcards(int num_pat, char_u **pat, int *num_file, char_u *