haproxy: enable hitless reloads

Switch HAProxy to a master/worker (-W) model, allowing for correct
handling of HUP signals. To do listening FD handoff, a stats socket with
'expose-fd listeners' needs to be part of the configuration file.

srcpkgs/haproxy/files/haproxy.cfg

@@ -2,6 +2,7 @@ global
   chroot /var/lib/haproxy
   user haproxy
   group haproxy
+  stats socket /var/run/haproxy.sock mode 0600 level admin expose-fd listeners process 1/1
 
 defaults
   mode http

srcpkgs/haproxy/files/haproxy/run

@@ -1,3 +1,3 @@
 #!/bin/sh
 
-exec haproxy -f /etc/haproxy/haproxy.cfg
+exec haproxy -W -f /etc/haproxy/haproxy.cfg

srcpkgs/haproxy/template

@@ -1,7 +1,7 @@
 # Template file for 'haproxy'
 pkgname=haproxy
 version=2.4.2
-revision=1
+revision=2
 build_style=gnu-makefile
 make_install_args="SBINDIR=${DESTDIR}/usr/bin DOCDIR=${DESTDIR}/usr/share/doc/${pkgname}"
 hostmakedepends="lua53-devel"