Add missing include (to fix compile error on FreeBSD)

panda/src/pgraph/nodePath.cxx

@@ -71,6 +71,7 @@
 #include "modelNode.h"
 #include "py_panda.h"
 #include "bam.h"
+#include "bamWriter.h"
 
 // stack seems to overflow on Intel C++ at 7000.  If we need more than 
 // 7000, need to increase stack size.