[src] Fix build of online feature extraction with older CUDA version (#3415)

Author: luitjens

src/cudafeat/online-ivector-feature-cuda.cc

@@ -243,6 +243,7 @@ void IvectorExtractorFastCuda::ComputeIvectorFromStats(
  // Forming new non-SP matrix for cusolver.
  CuMatrix<float> A(quadratic);
 
+#if CUDA_VERSION >= 9010
  // This is the cusolver return code. Checking it would require
  // synchronization.
  // So we do not check it.
@@ -269,7 +270,10 @@ void IvectorExtractorFastCuda::ComputeIvectorFromStats(
  A.Data(), A.Stride(), ivector->Data(), ivector_dim_, d_info));
 
  CuDevice::Instantiate().Free(workspace);
-
+#else
+ KALDI_ERROR << "Online Ivectors in CUDA is not supported by your CUDA version. "
+ << "Upgrade to CUDA 9.1 or later";
+#endif
  // remove prior
  CuSubVector<float> ivector0(*ivector, 0, 1);
  ivector0.Add(-prior_offset_);