QUIC: reworked migration handling. The quic connection now holds active, backup and probe paths instead of sockets. The number of migration paths is now limited and cannot be inflated by a bad client or an attacker. The client id is now associated with path rather than socket. This allows to simplify processing of output and connection ids handling. New migration abandons any previously started migrations. This allows to free consumed client ids and request new for use in future migrations and make progress in case when connection id limit is hit during migration. A path now can be revalidated without losing its state. The patch also fixes various issues with NAT rebinding case handling: - paths are now validated (previously, there was no validation and paths were left in limited state) - attempt to reuse id on different path is now again verified (this was broken in 40445fc7c403) - former path is now validated in case of apparent migration

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


echo $ngx_n "checking for uintptr_t ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for uintptr_t

END

found=no

cat << END > $NGX_AUTOTEST.c

#include <sys/types.h>
$NGX_INCLUDE_INTTYPES_H

int main(void) {
    uintptr_t i = 0;
    return (int) i;
}

END

ngx_test="$CC $CC_TEST_FLAGS $CC_AUX_FLAGS \
          -o $NGX_AUTOTEST $NGX_AUTOTEST.c $NGX_LD_OPT"

eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

if [ -x $NGX_AUTOTEST ]; then
    echo " uintptr_t found"
    found=yes
else
    echo $ngx_n " uintptr_t not found" $ngx_c
fi

rm -rf $NGX_AUTOTEST*


if [ $found = no ]; then
    found="uint`expr 8 \* $ngx_ptr_size`_t"
    echo ", $found used"

    echo "typedef $found  uintptr_t;"                   >> $NGX_AUTO_CONFIG_H
    echo "typedef $found  intptr_t;" | sed -e 's/u//g'  >> $NGX_AUTO_CONFIG_H
fi