fix: previous_op_count may more than op_count case process data compete

[ZYV037]

I met this under mips64 debian.

cmd: su - trinity -c "/home/trinity/trinity-master/trinity -N 1000000"

uname -a: Linux version 4.19.0-loongson-3-server #1187 SMP PREEMPT Wed Mar 25 22:36:49 CST 2020 mips64 GNU/Linux

Error Log: [main] Execcount went backwards! (old:126247 new:126240): [main] Bailing main loop because SHM was corrupted!. [main] Ran 126242 syscalls. Successes: 26475 Failures: 98421

trinity.log

[ZYV037]

Please check.

[kernelslacker]

very subtle, this took me a few reads to understand. good catch.