Merge branch 'jk/drop-release-pack-memory'

xmalloc() used to have a mechanism to ditch memory and address space resources as the last resort upon seeing an allocation failure from the underlying malloc(), which made the code complex and thread-unsafe with dubious benefit, as major memory resource users already do limit their uses with various other mechanisms. It has been simplified away. * jk/drop-release-pack-memory: packfile: drop release_pack_memory()