Fix linking against NAG on Mac 10.9 - requires a self compiled NAG library (libnagmac64) that I will make available soon.

gbatchG4PG.exe works just fine on Mac now with NAG enabled - delivering identical MCs compared to an linuxx8664icc results for various datacards that I tested.
Very useful for profiling the "real MC" using Instruments (Memory Allocations, Time Profiler, Cache performance, CPU utilization, etc..)