Configure: fixed clang detection on MINIX. As per POSIX, basic regular expressions have no alternations, and the interpretation of the "\|" construct is undefined. At least on MINIX and Solaris grep interprets "\|" as literal "|", and not as an alternation as GNU grep does. Removed such constructs introduced in f1daa0356a1d. This fixes clang detection on MINIX.

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


cat << END >> $NGX_AUTO_CONFIG_H

#ifndef $have
#define $have  $value
#endif

END