component/userhosts: use github.com/figiel/hosts for compatibility with recent libc

In ubuntu 21.04 (libc6 2.33-0ubuntu5) or current debian testing
(libc6 2.32-5) no longer use open to open /etc/hosts, but what appears
as "openat" in strace output - but can not be replaced by defining an
openat function.

This uses https://github.com/figiel/hosts which uses another approach
of replacing getaddrinfo, gethostbyname* and inet_aton.

Users have been updated a bit, because there are some small differences:
 - the /etc/hosts replacement file is defined by HOSTS_FILE environment
   variable, not HOSTS
 - the library name is libuserhosts.so, not userhosts.so

Other notable differences, for which we did not need code change are:
 - the new library also try to load a file when HOSTS_FILE is not set
 - the new library still use original /etc/hosts file
 - the new library supports aliases to hostnames, not only ip addresses

component/userhosts/buildout.cfg

 [userhosts]
 recipe = slapos.recipe.cmmi
 shared = true
-url = https://lab.nexedi.com/nexedi/userhosts/repository/${:revision}/archive.tar.gz
-revision = a05fe5a3a5cb7005351ef4ec41460089f3ce4d0a
-md5sum = 5a80b4d962d975f290a60cf790c3334d
+url = https://github.com/figiel/hosts/archive/${:revision}.tar.gz
+revision = fdb45fe219593d63453f4be55cfc2a1199c18f59
+md5sum = 9ff5407132a2a67200ef1036a02f0ee2
 configure-command = true
 make-options = PREFIX=@@LOCATION@@
-make-targets = check install
+make-targets = test install

stack/erp5/buildout.hash.cfg

@@ -70,7 +70,7 @@ md5sum = cc19560b9400cecbd23064d55c501eec
 
 [template]
 filename = instance.cfg.in
-md5sum = 9c417abd68f232b20b3cc1288155f0ae
+md5sum = 81c26ad203d943d3b6c46f3de4d7c34a
 
 [monitor-template-dummy]
 filename = dummy.cfg
@@ -86,7 +86,7 @@ md5sum = 0648e38bd5d3a15bb9f93264932740b9
 
 [template-zope]
 filename = instance-zope.cfg.in
-md5sum = 82d14f1a98197eaf986bcde3318dc870
+md5sum = a3b1f274569cec373d711a2f802a16ab
 
 [template-balancer]
 filename = instance-balancer.cfg.in

stack/erp5/instance-zope.cfg.in

@@ -176,7 +176,7 @@ context = key host_dict hosts-parameter:host-dict
 recipe = slapos.recipe.template:jinja2
 mode = 755
 template = inline:#!{{ parameter_dict['dash'] }}/bin/dash
-  export HOSTS=${hosts:rendered}
+  export HOSTS_FILE=${hosts:rendered}
   export LD_PRELOAD={{ parameter_dict['userhosts'] }}:$LD_PRELOAD
   exec "$@"
 rendered = ${directory:bin}/userhosts

stack/erp5/instance.cfg.in

@@ -103,7 +103,7 @@ link-binary = {{ dumps(zope_link_binary) }}
 fonts = {{ dumps(zope_fonts) }}
 fontconfig-includes = {{ dumps(zope_fontconfig_includes) }}
 template-fonts-conf = {{ dumps(template_fonts_conf) }}
-userhosts = {{ userhosts_location }}/lib/userhosts.so
+userhosts = {{ userhosts_location }}/lib/libuserhosts.so
 site-zcml = {{ site_zcml }}
 extra-path-list = {{ dumps(extra_path_list) }}
 matplotlibrc = {{ matplotlibrc_location }}