patch 8.2.1442: outdated references to the Mac Carbon GUI

Problem:    Outdated references to the Mac Carbon GUI.
Solution:   Remove or update references. (Yee Cheng Chin, closes #6703)
diff --git a/src/configure.ac b/src/configure.ac
index e17a74c..a2683a6 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -2433,8 +2433,7 @@
     yes|"")	AC_MSG_RESULT(yes - automatic GUI support)
     		gui_auto=yes ;;
     auto)	AC_MSG_RESULT(auto - disable GUI support for Mac OS) ;;
-    *)		AC_MSG_RESULT([Sorry, $enable_gui GUI is not supported])
-		SKIP_CARBON=YES ;;
+    *)		AC_MSG_RESULT([Sorry, $enable_gui GUI is not supported]) ;;
   esac
 else