patch 8.1.2281: 'showbreak' cannot be set for one window

Problem:    'showbreak' cannot be set for one window.
Solution:   Make 'showbreak' global-local.
diff --git a/src/structs.h b/src/structs.h
index 69dc782..87da168 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -254,6 +254,10 @@
     char_u	*wo_cc;
 # define w_p_cc w_onebuf_opt.wo_cc	// 'colorcolumn'
 #endif
+#ifdef FEAT_LINEBREAK
+    char_u	*wo_sbr;
+#define w_p_sbr w_onebuf_opt.wo_sbr	// 'showbreak'
+#endif
 #ifdef FEAT_STL_OPT
     char_u	*wo_stl;
 #define w_p_stl w_onebuf_opt.wo_stl	// 'statusline'