- archives are 2-byte aligned, and if we malloc the
- memory then we can be given memory above 2^32, so we
- mmap some anonymous memory and use that. We could
- do better here. */
+ archives are 2-byte aligned. When possible we use mmap
+ to get some anonymous memory, as on 64-bit platforms if
+ we use malloc then we can be given memory above 2^32.
+ In the mmap case we're probably wasting lots of space;
+ we could do better. */
+#ifdef USE_MMAP