Revert "fix byte order for un/packing RGBA32"

This reverts commit 8a34adb3681d021ac907f44444a9b9ad42bb8109.
add support for foreign C types
cabal wibbles
cabal: put extension pragmas in the individual files
cabal wibble
fix type C instances for 32-bit ghc

ping: AccelerateHS/accelerate#91