patch 8.1.1230: a lot of code is shared between vim.exe and gvim.exe

Problem:    A lot of code is shared between vim.exe and gvim.exe.
Solution:   Optionally put the shared code in vim.dll. (Ken Takata,
            closes #4287)
diff --git a/src/syntax.c b/src/syntax.c
index 7545165..b492505 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -8280,6 +8280,13 @@
      * background/foreground colors. */
     mch_set_normal_colors();
 #else
+# ifdef VIMDLL
+    if (!gui.in_use)
+    {
+	mch_set_normal_colors();
+	return;
+    }
+# endif
     cterm_normal_fg_color = 0;
     cterm_normal_fg_bold = 0;
     cterm_normal_bg_color = 0;
@@ -9823,7 +9830,7 @@
 #endif
 
 #if (defined(MSWIN) \
-	&& !defined(FEAT_GUI_MSWIN) \
+	&& (!defined(FEAT_GUI_MSWIN) || defined(VIMDLL)) \
 	&& defined(FEAT_TERMGUICOLORS)) || defined(PROTO)
     void
 syn_id2cterm_bg(int hl_id, int *fgp, int *bgp)