More robust hostmemory

Fix https://gitlab.com/astron-idg/idg/-/issues/30, by addressing some memory allocation issues.

This change fixes a CUDA exception when running the following wsclean command:

wsclean \
  -no-update-model-required \
  -minuv-l 20.0 \
  -size 1600 1600 \
  -reorder \
  -weight briggs -0.5 -weighting-rank-filter 3 \
  -clean-border 1 \
  -parallel-reordering 6 \
  -padding 1.2 \
  -auto-mask 2.5 \
  -auto-threshold 0.5 \
  -pol i \
  -name TTT \
  -scale 6arcsec \
  -niter 10 \
  -use-idg -idg-mode hybrid \
  -mgain 0.8 \
  -fit-beam \
  test.ms

The test.ms file was obtained from Reinout van Weeren.