vim-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 vim/vim#11835)

0ef9a5c094

src/nvim/ex_docmd.c

@@ -2852,7 +2852,7 @@ bool checkforcmd(char **pp, const char *cmd, int len)
       break;
     }
   }
-  if (i >= len && !isalpha((uint8_t)(*pp)[i])) {
+  if (i >= len && !ASCII_ISALPHA((*pp)[i])) {
     *pp = skipwhite(*pp + i);
     return true;
   }