fs/freevxfs/: add #include's

Every file should #include the headers containing the prototypes for
it's global functions.

Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/fs/freevxfs/vxfs_olt.c b/fs/freevxfs/vxfs_olt.c
index 1334762..76a0708 100644
--- a/fs/freevxfs/vxfs_olt.c
+++ b/fs/freevxfs/vxfs_olt.c
@@ -36,6 +36,7 @@
 
 #include "vxfs.h"
 #include "vxfs_olt.h"
+#include "vxfs_extern.h"
 
 
 static inline void