vim-patch:9.1.1331: Leaking memory with cmdcomplete()

Problem:  Leaking memory with cmdcomplete()
          (zeertzjq, after v9.1.1329)
Solution: free the memory (Girish Palya)

closes: vim/vim#17190

5c3d1e3258

Co-authored-by: Girish Palya <girishji@gmail.com>

src/nvim/cmdexpand.c

@@ -1065,6 +1065,7 @@ int showmatches(expand_T *xp, bool wildmenu)
 
   // Save cmdline before expansion
   if (ccline->cmdbuff != NULL) {
+    xfree(cmdline_orig);
     cmdline_orig = xstrnsave(ccline->cmdbuff, (size_t)ccline->cmdlen);
   }