message: Fix floating point exception in Linux guntest
  Since moving to `o2` defaults, the Linux CI check has been failing in
  AliRoot-guntest with a floating point exception. Peter tracked this down to a
  value `> 1.0` being passed to `asin` and provided this fix.
  Written-by: Peter Hristov
diff: @@ -751,6 +751,10 @@ Int_t AliITStrackerMI::PropagateBack(AliESDEvent *event) {
  dst2 = dxs*dxs + dys*dys;
  double dxy = TMath::Sqrt(dst2), arg = crvh*dxy;
  if (arg > kWatchStep) { // correct circular part for arc/segment factor
  + if (arg > 1.0) {
  + // Clamp "arg" to be <=1.0, to avoid errors from TMath::Asin below.
  + arg = 1.0;
  + }
  double dst = 1./crvh*TMath::ASin(arg);
  dst2 *= dst*dst;
  }
  