Fix distcheck target for swig binding generation

Signed-off-by: Matt Colyer <matt@colyer.name>
diff --git a/swig/Makefile.am b/swig/Makefile.am
index 726014b..d65b984 100644
--- a/swig/Makefile.am
+++ b/swig/Makefile.am
@@ -1,4 +1,4 @@
-INCLUDES = -I$(top_srcdir)/include  $(libplist_CFLAGS) -I$(includedir)
+INCLUDES = -I$(top_srcdir)/include  $(libplist_CFLAGS) -I$(oldincludedir)
 
 BUILT_SOURCES = iphone_wrap.c
 SWIG_SOURCES = iphone.i