REGTEST/MINOR: Unexpected curl URL globling.

With certain curl versions URLs which contain brackets may be interpreted
by the "URL globbing parser". This patch ensures that such brackets
are escaped.

Thank you to Ilya Shipitsin for having reported this issue.

reg-tests/ssl/h00000.vtc

@@ -34,7 +34,7 @@ haproxy h1 -conf {
 shell {
     HOST=${h1_frt_addr}
     if [ "${h1_frt_addr}" = "::1" ] ; then
-        HOST="[::1]"
+        HOST="\[::1\]"
     fi
     for i in 1 2 3 4 5; do
         curl -i -k https://$HOST:${h1_frt_port} & pids="$pids $!"