[gexiv2] Don't fail if vapigen is not avaliable

[Jens Georg <jensgeorg src gnome org>]

commit 0791cf42449cc33e290978a20117a2b8d2ad8a9a
Author: Jens Georg <mail jensge org>
Date:   Tue Aug 9 22:04:31 2016 +0200

    Don't fail if vapigen is not avaliable
    
    Signed-off-by: Jens Georg <mail jensge org>

 Makefile.am |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 17cb807..7b5862f 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -44,7 +44,7 @@ endif
 
 vapi: gexiv2.vapi
 
-if HAVE_INTROSPECTION
+if ENABLE_VAPIGEN
 gexiv2.vapi: gexiv2_vapi.stamp
        @true