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/option.h b/src/option.h
index 1154aa8..2a4ffba 100644
--- a/src/option.h
+++ b/src/option.h
@@ -1271,6 +1271,9 @@
     , WV_CULOPT
     , WV_CC
 #endif
+#ifdef FEAT_LINEBREAK
+    , WV_SBR
+#endif
 #ifdef FEAT_STL_OPT
     , WV_STL
 #endif