patch 9.1.1731: Not using const qualifier for opchars

Problem:  Not using const qualifier
Solution: Mark the opchars array const

closes: #18196

Signed-off-by: Damien Lejay <damien@lejay.be>
Signed-off-by: Christian Brabandt <cb@256bit.org>

src/ops.c

@@ -30,7 +30,7 @@ static void	pbyte(pos_T lp, int c);
  * IMPORTANT: Index must correspond with defines in vim.h!!!
  * The third field holds OPF_ flags.
  */
-static char opchars[][3] =
+static const char opchars[][3] =
 {
     {NUL, NUL, 0},			// OP_NOP
     {'d', NUL, OPF_CHANGE},		// OP_DELETE

src/version.c

@@ -724,6 +724,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1731,
 /**/
     1730,
 /**/