configure.ac: Remove AC_CHECK_FUNC for pipe now that gnulib::pipe used.

* configure.ac: Remove AC_CHECK_FUNC for pipe after cset 7f3519e6194a.

Author: Rik

configure.ac

@@ -2300,7 +2300,7 @@ AC_CHECK_FUNCS([getegid geteuid getgid getgrent getgrgid getgrnam])
 AC_CHECK_FUNCS([getpgrp getpid getppid getpwent getpwuid getuid])
 AC_CHECK_FUNCS([isascii kill])
 AC_CHECK_FUNCS([lgamma lgammaf lgamma_r lgammaf_r])
-AC_CHECK_FUNCS([log1p log1pf pipe])
+AC_CHECK_FUNCS([log1p log1pf])
 AC_CHECK_FUNCS([realpath resolvepath roundl])
 AC_CHECK_FUNCS([select setgrent setpwent siglongjmp strsignal])
 AC_CHECK_FUNCS([tcgetattr tcsetattr tgammaf toascii])