Filtering duplicate addresses in listen (ticket #2400). Due to the glibc bug[1], getaddrinfo("localhost") with AI_ADDRCONFIG on a typical host with glibc and without IPv6 returns two 127.0.0.1 addresses, and therefore "listen localhost:80;" used to result in "duplicate ... address and port pair" after 4f9b72a229c1. Fix is to explicitly filter out duplicate addresses returned during resolution of a name. [1] https://sourceware.org/bugzilla/show_bug.cgi?id=14969

# Copyright (C) Nginx, Inc.


if [ $USE_THREADS = YES ]; then

    if [ "$NGX_PLATFORM" = win32 ]; then
        cat << END

$0: --with-threads is not supported on Windows

END
        exit 1
    fi

    have=NGX_THREADS . auto/have
    CORE_DEPS="$CORE_DEPS $THREAD_POOL_DEPS"
    CORE_SRCS="$CORE_SRCS $THREAD_POOL_SRCS"
    CORE_LIBS="$CORE_LIBS -lpthread"
    NGX_LIBPTHREAD="-lpthread"
fi