build: add sdbus++-gen-meson generated files

Use the tool to generate the meson.build files for the current
tree of interfaces, but do not utilize them yet.  Add a
small helper tool to regenerate as needed.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ie1f68984e5b01dcab661863d2ac719d0e3cd45c1
diff --git a/gen/com/ibm/ipzvpd/VSBP/meson.build b/gen/com/ibm/ipzvpd/VSBP/meson.build
new file mode 100644
index 0000000..1b660c4
--- /dev/null
+++ b/gen/com/ibm/ipzvpd/VSBP/meson.build
@@ -0,0 +1,14 @@
+# Generated file; do not modify.
+generated_sources += custom_target(
+    'com/ibm/ipzvpd/VSBP__cpp'.underscorify(),
+    input: [ meson.source_root() / 'com/ibm/ipzvpd/VSBP.interface.yaml',  ],
+    output: [ 'server.cpp', 'server.hpp', 'client.hpp',  ],
+    command: [
+        sdbuspp_gen_meson_prog, '--command', 'cpp',
+        '--output', meson.current_build_dir(),
+        '--tool', sdbusplusplus_prog,
+        '--directory', meson.source_root(),
+        'com/ibm/ipzvpd/VSBP',
+    ],
+)
+