treewide: Leverage sdbus++-gen-meson

This makes us more consistent with other projects instead of writing
meson builds for sdbus++ by hand.

Change-Id: I38b69bc67b6a3d80cda1b508a76e106a50d8ab93
Signed-off-by: Willam A. Kennington III <wak@google.com>
diff --git a/example/gen/meson.build b/example/gen/meson.build
new file mode 100644
index 0000000..2756633
--- /dev/null
+++ b/example/gen/meson.build
@@ -0,0 +1,14 @@
+# Generated file; do not modify.
+sdbuspp_gen_meson_ver = run_command(
+    sdbuspp_gen_meson_prog,
+    '--version',
+).stdout().strip().split('\n')[0]
+
+if sdbuspp_gen_meson_ver != 'sdbus++-gen-meson version 4'
+    warning('Generated meson files from wrong version of sdbus++-gen-meson.')
+    warning(
+        'Expected "sdbus++-gen-meson version 4", got:',
+        sdbuspp_gen_meson_ver
+    )
+endif
+