src: Fix non-installed types.hpp

Change-Id: Ib2d53f9fe1c99ea4e33877441a75a3dc9962b6ba
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/meson.build b/src/meson.build
index ebe678c..c41f6bf 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -71,6 +71,7 @@
   'sdeventplus/clock.hpp',
   'sdeventplus/event.hpp',
   'sdeventplus/exception.hpp',
+  'sdeventplus/types.hpp',
   subdir: 'sdeventplus')
 
 install_headers(