patch 8.2.2581: Vim9: sourcing Vim9 script triggers a redraw

Problem:    Vim9: sourcing Vim9 script triggers a redraw.
Solution:   Do not let setting/restoring 'cpoptions' cause a redraw.
            (closes #7920)
diff --git a/src/vim.h b/src/vim.h
index e27bf8b..5dd69f6 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -1200,6 +1200,7 @@
 #define OPT_WINONLY	0x10	// only set window-local options
 #define OPT_NOWIN	0x20	// don't set window-local options
 #define OPT_ONECOLUMN	0x40	// list options one per line
+#define OPT_NO_REDRAW	0x80	// ignore redraw flags on option
 
 // Magic chars used in confirm dialog strings
 #define DLG_BUTTON_SEP	'\n'