Towards getting simpleFitExample working on Mac

(Sorry for mixing stuping whitespace changes with actual changes ... we can just use this for discussion and never merge it.)

I had to make a few changes to make `simpleFitExample` build on Mac OS X 10.8 with CUDA 5.0, V0.2.1221.

- Consistently add `-m64` flag to avoid link errors
- `+LIBS += -L$(CUDALOCATION)/lib` instead of `+LIBS += -L$(CUDALOCATION)/lib64` ... this maybe has to be set platform-dependent? (see also https://github.com/thrust/thrust/issues/356 ).
- The change to the `rootstuff` Makefile discussed in issue #3.

The `simpleFitExample` now builds fine, but it crashes after a few seconds  like this:
```
$ ./simpleFitExample 
Assertion failed: (host_fcn_ptr), function getMetricPointer, file /Users/deil/code/GooFit/FPOINTER/ThrustPdfFunctor.cu, line 171.
Abort trap: 6
```

@RolfAndreassen Is this the crash we discussed in Saas Fee? Do you have a solution / workaround? If this is a CUDA or Thrust bug maybe we can report it?