[easytag] Fix compilation when WavPack support is enabled

[David King <davidk src gnome org>]

commit 2e000acdede6e08e81e28cdee656284af7beea3c
Author: David King <amigadave amigadave com>
Date:   Fri Mar 27 14:32:21 2015 +0100

    Fix compilation when WavPack support is enabled
    
    https://bugzilla.gnome.org/show_bug.cgi?id=746372

 src/tags/wavpack_private.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/tags/wavpack_private.c b/src/tags/wavpack_private.c
index 2346c7f..63e5838 100644
--- a/src/tags/wavpack_private.c
+++ b/src/tags/wavpack_private.c
@@ -18,6 +18,8 @@
 
 #include "wavpack_private.h"
 
+#ifdef ENABLE_WAVPACK
+
 /* For EOF. */
 #include <stdio.h>
 
@@ -180,3 +182,5 @@ wavpack_write_bytes (void *id,
 
     return bytes_written;
 }
+
+#endif /* ENABLE_WAVPACK */