#18 dspsr: segfaults on small nsmear

[Willem van Straten]

e.g.

apsr@apsr17 benchmarking]$ dspsr -F32:D -x 16:2 -U minX1 -t 8 2bit_benchmark.dada
setting smearing samples to 2
setting smearing samples to 2
setting smearing samples to 2
setting smearing samples to 2
setting smearing samples to 2
setting smearing samples to 2
setting smearing samples to 2
setting smearing samples to 2
dspsr: using 1 times minimum blocksize, or 512 samples
(equivalent to -U 0.01611328125)
dsp::WeightedTimeSeries::get_nweights FATAL ERROR:
weights=0x2aaab034a5d0 + nweights=3 > base=0x2aaab034a5b0 + size=10 (weight_idat=320)
Segmentation fault