vim-patch:9.0.1783: Display issues with virt text smoothscroll and showbreak

Problem:  Wrong display with wrapping virtual text or unprintable chars,
          'showbreak' and 'smoothscroll'.
Solution: Don't skip cells taken by 'showbreak' in screen lines before
          "w_skipcol". Combined "n_skip" and "skip_cells".

closes: vim/vim#12597

b557f48982

src/nvim/plines.h

@@ -19,6 +19,7 @@ typedef struct {
   MarkTreeIter cts_iter[1];
 
   int cts_vcol;                  ///< virtual column at current position
+  int cts_max_head_vcol;         ///< see win_lbr_chartabsize()
 } chartabsize_T;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS