Bug#195018: [patch] make DynamicMMap dynamic

[Daniel Burrows <dburrows@debian.org>]

On Fri, Apr 27, 2007 at 03:46:05PM +0200, Michael Vogt <mvogt@acm.org> was heard to say:
> It also changes the non-file backed operation mode to use anonymous
> mmap instead of new char[]. 

  Does this solve an observed problem?  I'd expect these to do
more-or-less the same thing.  (won't matter for small amounts, and the
C++ allocator should be using anonymous mmap for large allocations).

  The one advantage I see (which could be considerable!) is that
mremap() avoids copies.  Does this save enough time to make it worth
using a more opaque idiom?  (I don't know the answer)

  Other than that, the code looks OK to me (haven't tested it).

  Daniel