refactor(screen.c): resolve all clint errors (#19754)

Co-authored-by: zeertzjq <zeertzjq@outlook.com>
Co-authored-by: Christian Clason <c.clason@uni-graz.at>

src/nvim/buffer_defs.h

@@ -431,7 +431,7 @@ typedef struct {
 typedef struct {
   hashtab_T b_keywtab;                  // syntax keywords hash table
   hashtab_T b_keywtab_ic;               // idem, ignore case
-  int b_syn_error;                      // TRUE when error occurred in HL
+  bool b_syn_error;                     // true when error occurred in HL
   bool b_syn_slow;                      // true when 'redrawtime' reached
   int b_syn_ic;                         // ignore case for :syn cmds
   int b_syn_foldlevel;                  // how to compute foldlevel on a line