patch 9.0.1215: using isalpha() adds dependency on current locale

Problem:    Using isalpha() adds dependency on current locale.
Solution:   Do not use isalpha() for recognizing a URL or the end of an Ex
            command. (closes #11835)

src/ex_docmd.c

@@ -2747,7 +2747,7 @@ checkforcmd_opt(
     for (i = 0; cmd[i] != NUL; ++i)
 	if (((char_u *)cmd)[i] != (*pp)[i])
 	    break;
-    if (i >= len && !isalpha((*pp)[i]) && (*pp)[i] != '_'
+    if (i >= len && !ASCII_ISALPHA((*pp)[i]) && (*pp)[i] != '_'
 			 && (!noparen || ((*pp)[i] != '(' && (*pp)[i] != '.')))
     {
 	*pp = skipwhite(*pp + i);

src/misc1.c

@@ -2699,11 +2699,11 @@ path_with_url(char_u *fname)
     // non-URL text.
 
     // first character must be alpha
-    if (!isalpha(*fname))
+    if (!ASCII_ISALPHA(*fname))
 	return 0;
 
     // check body: alpha or dash
-    for (p = fname + 1; (isalpha(*p) || (*p == '-')); ++p)
+    for (p = fname + 1; (ASCII_ISALPHA(*p) || (*p == '-')); ++p)
 	;
 
     // check last char is not a dash

src/option.c

@@ -1684,7 +1684,7 @@ do_set(
 	errmsg = NULL;
 	startarg = arg;		// remember for error message
 
-	if (STRNCMP(arg, "all", 3) == 0 && !isalpha(arg[3])
+	if (STRNCMP(arg, "all", 3) == 0 && !ASCII_ISALPHA(arg[3])
 						&& !(opt_flags & OPT_MODELINE))
 	{
 	    /*

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1215,
 /**/
     1214,
 /**/