move wx11 and (the rest of) wxMGL specific checks into /chkconf.h file

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@40410 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/mgl/chkconf.h

@@ -14,6 +14,12 @@
 #ifndef _WX_MGL_CHKCONF_H_
 #define _WX_MGL_CHKCONF_H_
 
+
+/* wxPalette is always needed */
+#if !wxUSE_PALETTE
+#   error "wxMGL requires wxUSE_PALETTE=1"
+#endif
+
 /*
    wxDisplay is not implemented for OS/2, use stub common version instead.
  */