patch 8.2.5013: after text formatting cursor may be in an invalid position

Problem:    After text formatting the cursor may be in an invalid position.
Solution:   Correct the cursor position after formatting.

src/testdir/test_textformat.vim

@@ -1291,4 +1291,16 @@ func Test_fo_2()
   close!
 endfunc
 
+" This was leaving the cursor after the end of a line.  Complicated way to
+" have the problem show up with valgrind.
+func Test_correct_cursor_position()
+  set encoding=iso8859
+  new
+  norm a000“0
+  sil! norm gggg0i0gw0gg
+
+  bwipe!
+  set encoding=utf8
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/textformat.c

@@ -870,6 +870,9 @@ op_format(
     {
 	curwin->w_cursor = saved_cursor;
 	saved_cursor.lnum = 0;
+
+	// formatting may have made the cursor position invalid
+	check_cursor();
     }
 
     if (oap->is_VIsual)

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    5013,
 /**/
     5012,
 /**/