patch 7.4.1919
Problem:    Register contents is not merged when writing viminfo.
Solution:   Use timestamps for register contents.
diff --git a/src/proto/ex_cmds.pro b/src/proto/ex_cmds.pro
index 3057a93..bc624bf 100644
--- a/src/proto/ex_cmds.pro
+++ b/src/proto/ex_cmds.pro
@@ -17,6 +17,7 @@
 char_u *viminfo_readstring(vir_T *virp, int off, int convert);
 void viminfo_writestring(FILE *fd, char_u *p);
 int barline_writestring(FILE *fd, char_u *s, int remaining_start);
+time_t vim_time(void);
 void do_fixdel(exarg_T *eap);
 void print_line_no_prefix(linenr_T lnum, int use_number, int list);
 void print_line(linenr_T lnum, int use_number, int list);