patch 8.1.2253: using "which" to check for an executable is not reliable

Problem:    Using "which" to check for an executable is not reliable.
Solution:   Use "command -v" instead.  Also exit with error code when
            generating tags has an error. (closes #5174)

src/version.c

@@ -741,6 +741,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2253,
 /**/
     2252,
 /**/