patch 8.1.0997: using GUI colors in vim.exe when 'termguicolors' is off

Problem:    Using GUI colors in vim.exe when 'termguicolors' is off.
Solution:   Add condition for 'termguicolors' set. (Ken Takata, closes #4078)
diff --git a/src/version.c b/src/version.c
index e1c8c61..539a1e1 100644
--- a/src/version.c
+++ b/src/version.c
@@ -780,6 +780,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    997,
+/**/
     996,
 /**/
     995,