Use a more useful expansion strategy when re-sizing the array, we use
this 150% in a lot of other places.

This takes the opening time from more than 4m (I lost patience) to under
5s.

Change-Id: I8511662947d737c26ec49503a75af8d4cf447f67
Reviewed-on: https://gerrit.libreoffice.org/73394
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>