Crypt the text in the undo file if the file itself is crypted.
diff --git a/src/proto/fileio.pro b/src/proto/fileio.pro
index e5a1b28..32e3045 100644
--- a/src/proto/fileio.pro
+++ b/src/proto/fileio.pro
@@ -2,6 +2,10 @@
void filemess __ARGS((buf_T *buf, char_u *name, char_u *s, int attr));
int readfile __ARGS((char_u *fname, char_u *sfname, linenr_T from, linenr_T lines_to_skip, linenr_T lines_to_read, exarg_T *eap, int flags));
int prep_exarg __ARGS((exarg_T *eap, buf_T *buf));
+int prepare_crypt_read __ARGS((FILE *fp));
+char_u *prepare_crypt_write __ARGS((buf_T *buf, int *lenp));
+size_t fwrite_crypt __ARGS((buf_T *buf, char_u *ptr, size_t len, FILE *fp));
+char_u *read_string_decrypt __ARGS((buf_T *buf, FILE *fd, int len));
int check_file_readonly __ARGS((char_u *fname, int perm));
int buf_write __ARGS((buf_T *buf, char_u *fname, char_u *sfname, linenr_T start, linenr_T end, exarg_T *eap, int append, int forceit, int reset_changed, int filtering));
void msg_add_fname __ARGS((buf_T *buf, char_u *fname));