src: Fix missing installed header

Change-Id: Iaccc74e3215022a22ec9b72136ed277856830867
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/meson.build b/src/meson.build
index d444b84..3ed9fd4 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -79,6 +79,7 @@
 install_headers(
   'stdplus/raw.hpp',
   'stdplus/signal.hpp',
+  'stdplus/types.hpp',
   subdir: 'stdplus')
 
 install_headers(