patch 9.1.1031: Coverity complains about insecure data handling

Problem:  Coverity complains about insecure data handling
          (v9.1.1024)
Solution: use int consistently to access the blob index
          (Yegappan Lakshmanan)

related: #16468

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: yegappan

src/fileio.c

@@ -4308,7 +4308,7 @@ buf_check_timestamp(
 	     */
 	    busy = TRUE;
 #ifdef FEAT_EVAL
-	    set_vim_var_string(VV_FCS_REASON, (char_u *)reason, reasonlen);
+	    set_vim_var_string(VV_FCS_REASON, (char_u *)reason, (int)reasonlen);
 	    set_vim_var_string(VV_FCS_CHOICE, (char_u *)"", 0);
 #endif
 	    ++allbuf_lock;

src/strings.c

@@ -1265,7 +1265,7 @@ string_from_blob(blob_T *blob, long *start_idx)
 {
     garray_T	str_ga;
     long	blen;
-    long	idx;
+    int		idx;
 
     ga_init2(&str_ga, sizeof(char), 80);
 

src/testdir/test_functions.vim

@@ -4282,6 +4282,9 @@ func Test_str2blob()
     call assert_equal(0zABBB0AABBB, str2blob(['«»', '«»'], {'encoding': 'latin1'}))
     call assert_equal(0zC2ABC2BB, str2blob(['«»'], {'encoding': 'utf8'}))
 
+    call assert_equal(0z62, str2blob(["b"], test_null_dict()))
+    call assert_equal(0z63, str2blob(["c"], {'encoding': test_null_string()}))
+
     call assert_fails("call str2blob(['abc'], [])", 'E1206: Dictionary required for argument 2')
     call assert_fails("call str2blob(['abc'], {'encoding': []})", 'E730: Using a List as a String')
     call assert_fails("call str2blob(['abc'], {'encoding': 'ab12xy'})", 'E1515: Unable to convert to ''ab12xy'' encoding')

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1031,
 /**/
     1030,
 /**/