configure: fixed typo, fixed detection of memory pagesize

configure.ac

@@ -1415,7 +1415,7 @@ have_inet6=no
 ])
 AC_MSG_RESULT($have_inet6)
 
-MHD_CHECK_FUNC([[sysconf]], [[#include <unitstd.h>]], [[long a = sysconf(0); if (a) return 1;]])
+MHD_CHECK_FUNC([[sysconf]], [[#include <unistd.h>]], [[long a = sysconf(0); if (a) return 1;]])
 
 HIDDEN_VISIBILITY_CFLAGS=""
 AS_CASE(["$host"],