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/meson.build b/example/meson.build
index b338dc1..17fd569 100644
--- a/example/meson.build
+++ b/example/meson.build
@@ -44,10 +44,16 @@
     dependencies: asio_dep,
 )
 
-subdir('net/poettering/Calculator')
+generated_sources = []
+generated_others = []
+subdir('gen')
+subdir('gen/net')
+
 executable(
     'calculator-server',
     'calculator-server.cpp',
-    calculator_sources,
+    generated_sources,
+    implicit_include_directories: false,
+    include_directories: include_directories('gen'),
     dependencies: sdbusplus_dep,
 )