Update FFT.java

1) Firstly, I added functionality to synchronize this thread "FFT" with thread 3 "CrackDetection" but then commented it because synchronization is working incorrect. Thread 3 "CrackDetection" is just called once without while(true) cycle, while threads 1 "ReadAudioData" and 2 "FFT" are called in infinite loops while(true) and synchronized with each other

2) Some comments removed