treewide: Create yaml directory

This allows the propagated yamldir paramter to work correctly in
subproject style builds. We don't want other files in the project
conflicting with tools that scan the yamldir.

Change-Id: Ie2759c7f3baf399392cdda0e507055ceb262d2e1
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/gen/com/ibm/ipzvpd/VER0/meson.build b/gen/com/ibm/ipzvpd/VER0/meson.build
index 9e83988..bc8e58d 100644
--- a/gen/com/ibm/ipzvpd/VER0/meson.build
+++ b/gen/com/ibm/ipzvpd/VER0/meson.build
@@ -1,13 +1,13 @@
 # Generated file; do not modify.
 generated_sources += custom_target(
     'com/ibm/ipzvpd/VER0__cpp'.underscorify(),
-    input: [ '../../../../../com/ibm/ipzvpd/VER0.interface.yaml',  ],
+    input: [ '../../../../../yaml/com/ibm/ipzvpd/VER0.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.current_source_dir() / '../../../../..',
+        '--directory', meson.current_source_dir() / '../../../../../yaml',
         'com/ibm/ipzvpd/VER0',
     ],
 )