Update to support LLVM 3.4.4.*

- Mostly superficial changes.
- `writeBitcodeToFile` and `writeObjectToFile` were causing
   crashes on my system, so I switched to using `moduleBitcode`
   and `moduleObject`, and just writing the ByteString to file
   manually.
- When compiling the IR code, LLVM complained about
  `__idris_floatFmtStr` having the wrong type. I don't know
  anything about LLVM IR code, so I just removed that function
  (and any that depend on it) from the Global declarations. This
  should probably be fixed.