Relaxed build dependencies a bit.

Author: svenpanne

GLUT.cabal

@@ -163,7 +163,7 @@ library
       build-depends: base >= 3 && < 5, array >= 0.3 && < 0.5, containers >= 0.3 && < 0.6
    else
       build-depends: base < 3
-   build-depends: OpenGL == 2.9.*, OpenGLRaw == 1.4.*
+   build-depends: OpenGL >= 2.8.0.0, OpenGLRaw >= 1.3.0.0
    ghc-options: -Wall -O2
    if os(windows) && flag(UseNativeWindowsLibraries)
       if arch(i386)