Don't use -O2, hopefully improving the Travis CI builds.

Author: svenpanne

OpenGLRaw.cabal

@@ -577,7 +577,7 @@ library
   include-dirs: include
   build-depends: base >= 3 && < 5
   default-language: Haskell2010
-  ghc-options: -Wall -O2
+  ghc-options: -Wall
   other-extensions: CPP
   if os(windows) && flag(UseNativeWindowsLibraries)
     if arch(i386)