Fix fltk-config (OpenGL and macOS)

This file has been missed by the conversion process:

- rename GLLIB to GLLIBS
- do not "bundle" apps on macOS if built with X11

fltk-config.in

@@ -1,10 +1,8 @@
 #!/bin/sh
 #
-# "$Id$"
-#
 # FLTK configuration utility.
 #
-# Copyright 2000-2016 by Bill Spitzak and others.
+# Copyright 2000-2021 by Bill Spitzak and others.
 # Original version Copyright 2000 by James Dean Palmer
 # Adapted by Vincent Penne and Michael Sweet
 #
@@ -12,11 +10,11 @@
 # the file "COPYING" which should have been included with this file.  If this
 # file is missing or damaged, see the license at:
 #
-#      http://www.fltk.org/COPYING.php
+#      https://www.fltk.org/COPYING.php
 #
-# Please report all bugs and problems on the following page:
+# Please see the following page on how to report bugs and issues:
 #
-#      http://www.fltk.org/str.php
+#      https://www.fltk.org/bugs.php
 #
 
 MAJOR_VERSION=@FL_MAJOR_VERSION@
@@ -243,8 +241,8 @@ if test x$use_forms = xyes; then
     LDSTATIC="$libdir/libfltk_forms.a $LDSTATIC"
 fi
 if test x$use_gl = xyes; then
-    LDLIBS="-lfltk_gl$SHAREDSUFFIX @GLLIB@ $LDLIBS"
-    LDSTATIC="$libdir/libfltk_gl.a @GLLIB@ $LDSTATIC"
+    LDLIBS="-lfltk_gl$SHAREDSUFFIX @GLLIBS@ $LDLIBS"
+    LDSTATIC="$libdir/libfltk_gl.a @GLLIBS@ $LDSTATIC"
 fi
 if test x$use_images = xyes; then
     LDLIBS="-lfltk_images$SHAREDSUFFIX $IMAGELIBS $LDLIBS"
@@ -291,7 +289,14 @@ if test -n "$compile"; then
 fi
 
 if test -n "$post"; then
-    case "`uname`" in
+    running=`uname`
+    if test "$running" = "Darwin"; then
+        # if FLTK targets MacOS+X11, apps need not be bundled
+        if test `echo $LDLIBS | fgrep -c -e " -lX11"` = 1; then
+            running=""
+        fi
+    fi
+    case $running in
 	Darwin)
 	    echo Creating "'$post.app'" bundle for desktop...
 	    id=`echo $post | tr ' ' '_'`
@@ -398,7 +403,3 @@ fi
 if test "$echo_includedir" = "yes"; then
     echo $includedir
 fi
-
-#
-# End of "$Id$".
-#