[PATCH] Configure: fix build with -Werror=return-type

[Piotr Sikora]

# HG changeset patch
# User Piotr Sikora <piotrsikora at google.com>
# Date 1476698417 25200
#      Mon Oct 17 03:00:17 2016 -0700
# Node ID ad0525e40183deb5dc2d5f1f85ee3f28c0762249
# Parent  8046b999aaaf95980e89a6d0620657bc4123342b
Configure: fix build with -Werror=return-type.

Signed-off-by: Piotr Sikora <piotrsikora at google.com>

diff -r 8046b999aaaf -r ad0525e40183 nxt/auto/clang
--- a/nxt/auto/clang
+++ b/nxt/auto/clang
@@ -198,6 +198,7 @@ nxt_feature_incs=
 nxt_feature_libs=
 nxt_feature_test="int main() {
                       __builtin_prefetch(0);
+                      return 0;
                   }"
 . ${NXT_AUTO}feature