MINOR: version: report "HAProxy" not "HA-Proxy" in the version output

MINOR: version: report "HAProxy" not "HA-Proxy" in the version output

When running "haproxy -v", we still get "HA-Proxy" which is the last
place where this confusing oddity happens. Being so used to it I didn't
even notice it until it was reported to me just after 2.2 but it never
got fixed, despite the PRODUCT_NAME macro that is used to report the
name in the stats page and in "show info" being already set to "HAProxy"
15 years ago in 1.2.14 with commit e03312613. It's about time to
uniformize everything.