build: add meson for unit-tests

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I96e75ba8a4853d0454f3f5012e0d79e1a34af02c
diff --git a/meson.build b/meson.build
index dfcad3d..e66c3c3 100644
--- a/meson.build
+++ b/meson.build
@@ -45,3 +45,7 @@
   install: true,
   install_dir: get_option('libdir') / 'ipmid-providers',
 )
+
+if get_option('tests').allowed()
+  subdir('test')
+endif