Update CTurbSSTSolver.cpp to fix a bug of calculate MuT. #8337

Job	Run time
Build SU2 (BaseMPI)	13m 21s
Build SU2 (ReverseMPI)	14m 14s
Build SU2 (ForwardMPI)	11m 32s
Build SU2 (BaseNoMPI)	7m 36s
Build SU2 (ReverseNoMPI)	12m 29s
Build SU2 (ForwardNoMPI)	9m 29s
Build SU2 (BaseOMP)	7m 49s
Build SU2 (ReverseOMP)	14m 54s
Build SU2 (ForwardOMP)	10m 53s
Build SU2 (asan) (BaseNoMPI-asan)	15m 23s
Build SU2 (asan) (ReverseNoMPI-asan)	44m 9s
Build SU2 (tsan) (BaseOMP-tsan)	11m 58s
Build SU2 (tsan) (ReverseOMP-tsan)	27m 46s
Regression Tests (vandv.py)	2m 17s
Regression Tests (tutorials.py)	5m 10s
Unit Tests (test_driver)	1m 0s
Regression Tests (parallel_regression.py)	14m 17s
Unit Tests (test_driver_AD)	46s
Regression Tests (parallel_regression_AD.py)	7m 35s
Unit Tests (test_driver_DD)	54s
Regression Tests (serial_regression.py)	16m 23s
Regression Tests (serial_regression_AD.py)	5m 11s
Regression Tests (hybrid_regression.py)	11m 36s
Regression Tests (hybrid_regression_AD.py)	3m 28s
Thread Sanitizer Tests (hybrid_regression.py)	28m 0s
Thread Sanitizer Tests (hybrid_regression_AD.py)	8m 35s
Address Sanitizer Tests (serial_regression.py)	14m 53s
Address Sanitizer Tests (serial_regression_AD.py)	5m 21s
	5h 26m 59s

Provide feedback