Update nfs-pthreads examples to specify number of threads and not chunk size per thread. This is more practical and works well for very lareg file sizes too.
Added multithreading and pthread detection to cmake.
Misc compiler warning fixes in examples code which was left from last time.
Testing done:
Validated nfs-pthreads-writefile and nfs-pthreads-async-writefile by transferring and checksumming 25GB file.
Testing done: