build: meson support for libphosphor-logging

Create just enough meson directives to create the equivalent
of libphosphor-logging, so that this repository can be picked
up as a meson subproject.  Remainder of the conversion to meson
will be in follow-on commits.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ifbcc58b118352d8f0338221c4cb7e472c2be7a43
diff --git a/meson_options.txt b/meson_options.txt
new file mode 100644
index 0000000..0a8c744
--- /dev/null
+++ b/meson_options.txt
@@ -0,0 +1,7 @@
+option('yamldir', type: 'string', description: 'Path to YAML')
+option(
+    'callout_yaml',
+    type: 'string',
+    value: 'callouts/callouts-example.yaml',
+    description: 'Path to Callout YAML',
+)