patch 8.1.2126: viminfo not sufficiently tested

Problem:    Viminfo not sufficiently tested.
Solution:   Add more test cases.  Clean up comments. (Yegappan Lakshmanan,
            closes #5032)

src/structs.h

@@ -1133,18 +1133,6 @@ typedef struct
     int		vc_fail;	// fail for invalid char, don't use '?'
 } vimconv_T;
 
-/*
- * Structure used for reading from the viminfo file.
- */
-typedef struct
-{
-    char_u	*vir_line;	// text of the current line
-    FILE	*vir_fd;	// file descriptor
-    vimconv_T	vir_conv;	// encoding conversion
-    int		vir_version;	// viminfo version detected or -1
-    garray_T	vir_barlines;	// lines starting with |
-} vir_T;
-
 /*
  * Structure used for the command line history.
  */