Configure: fixed clang version detection (closes #1539). While 325b3042edd6 fixed it on MINIX, it broke it on systems that output the word "version" on several lines with "cc -v". The fix is to only consider "clang version" or "LLVM version" as clang version, but this time only using sed(1).

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  0
#endif

END