patch 9.1.1072: 'diffopt' "linematch" cannot be used with {n} less than 10

Problem:  'diffopt' "linematch" cannot be used with {n} less than 10
          digits (after v9.1.1022)
Solution: Fix off-by-one error when checking for digit (zeertzjq)

closes: #16577

Signed-off-by: zeertzjq <[email protected]>
Signed-off-by: Christian Brabandt <[email protected]>

Author: zeertzjq

src/diff.c

@@ -2795,7 +2795,7 @@ diffopt_changed(void)
 	    else
 		return FAIL;
 	}
-	else if (STRNCMP(p, "linematch:", 10) == 0 && VIM_ISDIGIT(p[11]))
+	else if (STRNCMP(p, "linematch:", 10) == 0 && VIM_ISDIGIT(p[10]))
 	{
 	    p += 10;
 	    linematch_lines_new = getdigits(&p);

src/testdir/gen_opt_test.vim

@@ -178,9 +178,11 @@ let test_values = {
       \		'icase', 'iwhite', 'iwhiteall', 'horizontal', 'vertical',
       \		'closeoff', 'hiddenoff', 'foldcolumn:0', 'foldcolumn:12',
       \		'followwrap', 'internal', 'indent-heuristic', 'algorithm:myers',
-      \		'algorithm:minimal', 'algorithm:patience',
-      \		'algorithm:histogram', 'icase,iwhite'],
-      \		['xxx', 'foldcolumn:xxx', 'algorithm:xxx', 'algorithm:']],
+      \		'icase,iwhite', 'algorithm:minimal', 'algorithm:patience',
+      \		'algorithm:histogram', 'linematch:5'],
+      \		['xxx', 'foldcolumn:', 'foldcolumn:x', 'foldcolumn:xxx',
+      \		'linematch:', 'linematch:x', 'linematch:xxx', 'algorithm:',
+      \		'algorithm:xxx', 'context:', 'context:x', 'context:xxx']],
       \ 'display': [['', 'lastline', 'truncate', 'uhex', 'lastline,uhex'],
       \		['xxx']],
       \ 'eadirection': [['', 'both', 'ver', 'hor'], ['xxx', 'ver,hor']],

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1072,
 /**/
     1071,
 /**/