Windows: non-persistent cache from pagefile->heap

Windows: non-persistent cache from pagefile->heap

Change the non-persistent cache mode to use a heap allocated
cache in place of a paging file allocated cache.  With a heap
cache the memory for the cache can be locked into physical memory
so it won't be swapped out when running in virtual machines.
This patch does not apply such memory locking.

Change-Id: I85e6da1bba481d3d9bca84673b918b1d7cde71f9
Reviewed-on: http://gerrit.openafs.org/5343
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>