vim-patch:8.2.4812: unused struct item

Problem:    Unused struct item.
Solution:   Remove "lines" match_T.  Simplify the code. (closes vim/vim#10256)
8279cfe499

src/nvim/buffer_defs.h

@@ -1020,7 +1020,6 @@ typedef struct {
                         // match (may continue in next line)
   buf_T *buf;     // the buffer to search for a match
   linenr_T lnum;        // the line to search for a match
-  linenr_T lines;       // number of lines starting from lnum
   int attr;             // attributes to be used for a match
   int attr_cur;         // attributes currently active in win_line()
   linenr_T first_lnum;  // first lnum to search for multi-line pat