sdeventplus: Depend on function2

An upcoming change will require this dependency for sdeventplus, so that
we can store functions containing move-only types for callbacks.

Change-Id: Iecaae00eb471a18a0329e09640c6e30bd6a72895
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/recipes-extended/sdeventplus/sdeventplus_git.bb b/recipes-extended/sdeventplus/sdeventplus_git.bb
index d1ddff9..2f2ce35 100644
--- a/recipes-extended/sdeventplus/sdeventplus_git.bb
+++ b/recipes-extended/sdeventplus/sdeventplus_git.bb
@@ -9,6 +9,7 @@
 inherit meson pkgconfig
 
 DEPENDS += " \
+        function2 \
         stdplus \
         systemd \
         "