set the array capacity. If the array capacity isn't currently large enough to hold the requested capacity (in number of elements), then the array is resized/reallocated to the appropriate size. Pass in a requested capacity of 0 to get the current capacity. Returns the number of elements that can actually be stored once the resizing is done.
extern(C) ulong _d_arraysetcapacity (
Walter Bright, Sean Kelly, Steven Schveighoffer
Distributed under the Boost Software License 1.0. (See accompanying file LICENSE)