patch 8.1.1736: viminfo support is spread out

Problem:    Viminfo support is spread out.
Solution:   Move more viminfo code to viminfo.c. (Yegappan Lakshmanan,
            closes #4717)  Reorder code to make most functions static.

src/structs.h

@@ -3751,3 +3751,58 @@ typedef enum {
     FIND_POPUP,		// also find popup windows
     FAIL_POPUP		// return NULL if mouse on popup window
 } mouse_find_T;
+
+// Symbolic names for some registers.
+#define DELETION_REGISTER	36
+#ifdef FEAT_CLIPBOARD
+# define STAR_REGISTER		37
+#  ifdef FEAT_X11
+#   define PLUS_REGISTER	38
+#  else
+#   define PLUS_REGISTER	STAR_REGISTER	    // there is only one
+#  endif
+#endif
+#ifdef FEAT_DND
+# define TILDE_REGISTER		(PLUS_REGISTER + 1)
+#endif
+
+#ifdef FEAT_CLIPBOARD
+# ifdef FEAT_DND
+#  define NUM_REGISTERS		(TILDE_REGISTER + 1)
+# else
+#  define NUM_REGISTERS		(PLUS_REGISTER + 1)
+# endif
+#else
+# define NUM_REGISTERS		37
+#endif
+
+// Each yank register has an array of pointers to lines.
+typedef struct
+{
+    char_u	**y_array;	// pointer to array of line pointers
+    linenr_T	y_size;		// number of lines in y_array
+    char_u	y_type;		// MLINE, MCHAR or MBLOCK
+    colnr_T	y_width;	// only set if y_type == MBLOCK
+#ifdef FEAT_VIMINFO
+    time_t	y_time_set;
+#endif
+} yankreg_T;
+
+// The offset for a search command is store in a soff struct
+// Note: only spats[0].off is really used
+typedef struct soffset
+{
+    int		dir;		// search direction, '/' or '?'
+    int		line;		// search has line offset
+    int		end;		// search set cursor at end
+    long	off;		// line or char offset
+} soffset_T;
+
+// A search pattern and its attributes are stored in a spat struct
+typedef struct spat
+{
+    char_u	    *pat;	// the pattern (in allocated memory) or NULL
+    int		    magic;	// magicness of the pattern
+    int		    no_scs;	// no smartcase for this pattern
+    soffset_T	    off;
+} spat_T;