Don't build d3d8 if we don't have OpenGL support.

diff --git a/dlls/make_dlls b/dlls/make_dlls
index 90f3ebd..515bdc3 100755
--- a/dlls/make_dlls
+++ b/dlls/make_dlls
@@ -35,6 +35,7 @@
   "ddraw"    => "XFILES",
   "glu32"    => "GLU32FILES",
   "opengl32" => "OPENGLFILES",
+  "d3d8"     => "OPENGLFILES",
   "x11drv"   => "XFILES"
 );