vim-patch:9.0.0410: struct member cts_lnum is unused

Problem:    Struct member cts_lnum is unused.
Solution:   Delete it.
d7633114af

src/nvim/plines.h

@@ -6,7 +6,6 @@
 // Argument for lbr_chartabsize().
 typedef struct {
   win_T *cts_win;
-  linenr_T cts_lnum;   // zero when not using text properties
   char *cts_line;    // start of the line
   char *cts_ptr;     // current position in line