Fix svdtj tests for complex<float> on macOS.

The faster heuristic doesn't work so well for complex<float>.
See macOS test errors: https://cdash-ci.inria.fr/test/2751663

Extract:
==================== test 2: rel. error
svdtj input conf:
 J1: 0
 J2: 0
 t1: -1
 t2: -1
 tol: 0.1
 relErr: 1
 order: -1
 enable_large_Faust: 0
 matrix norm: 7.59428
 err_period: 100
U factor : 99, relative err.: 9.60274e-07
V factor : 99, relative err.: 6.40183e-07
SVDTJ iteration: 100, singular values approximate square norm error: 8.92282e-06
U factor : 199, relative err.: 1.49376e-06
V factor : 199, relative err.: 1.17367e-06
Warning: U approximate accuracy is not increasing anymore, stopped eigtj tunning for U.
        U current error: 1.49376e-06, previous error: 9.60274e-07
Warning: V approximate accuracy is not increasing anymore, stopped eigtj tunning for V.
        V current error: 1.17367e-06, previous error: 6.40183e-07
U, V number of factors: 100, 100
U, V RCGs: 0.930909 0.46556
[...]
svdtj norm err: -6.2789e-08
svdtj square norm err: -7.62939e-06
Assertion failed: (norm_err <= tol), function auto_tests, file /Users/ci/builds/sonxyZB3/0/faustgrp/faust/build_FaustMacOSPythonMatlab/run_test/src/test_svdtj_complexfloat.cpp, line 146.