tests/lcitool: Generate distribution packages list in JSON format

Add the generate_pkglist() helper to generate a list of packages
required by a distribution to build QEMU.

Since we can not add a "THIS FILE WAS AUTO-GENERATED" comment in
JSON, create the files under tests/vm/generated/ sub-directory;
add a README mentioning the files are generated.

Suggested-by: Erik Skultety <eskultet@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Message-Id: <20230711144922.67491-2-philmd@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/lcitool/refresh

@@ -84,6 +84,12 @@ def generate_cirrus(target, trailer=None):
     generate(filename, cmd, trailer)
 
 
+def generate_pkglist(vm, target):
+    filename = Path(src_dir, "tests", "vm", "generated", vm + ".json")
+    cmd = lcitool_cmd + ["variables", "--format", "json", target, "qemu"]
+    generate(filename, cmd, None)
+
+
 # Netmap still needs to be manually built as it is yet to be packaged
 # into a distro. We also add cscope and gtags which are used in the CI
 # test
@@ -191,6 +197,11 @@ try:
     generate_cirrus("freebsd-13")
     generate_cirrus("macos-12")
 
+    #
+    # VM packages lists
+    #
+    generate_pkglist("freebsd", "freebsd-13")
+
     sys.exit(0)
 except Exception as ex:
     print(str(ex), file=sys.stderr)

tests/vm/generated/README

@@ -0,0 +1,5 @@
+# FILES IN THIS FOLDER WERE AUTO-GENERATED
+#
+#  $ make lcitool-refresh
+#
+# https://gitlab.com/libvirt/libvirt-ci