haproxy: Add nossl variant

haproxy can be built without the huge libopenssl dependency to use it as
a simple http load balancer. This patch adds a haproxy-nossl variant to
the Makefile, which builds it with the USE_OPENSSL flag disabled. The
-lcrypto flag is also removed since it is handled by the haproxy
Makefile based on the USE_OPENSSL flag.

Signed-off-by: Vikraman Choudhury <vikraman@gentoo.org>