can we publish a aset interface?

Hello

I would to use a special memory context for shared data (based on
mmap) and I like impementation of aset. There is only one difference -
aset is based on malloc and I would to use a mmap.

malloc() is used in AllocSetContextCreate and AllocSetAlloc. These
procedures should be overwritten, but other code and data structures
can be used. This step can be useful for previous discuss about some
more comfortable maintaining of shared memory.

What do you think about?

Regards

Pavel Stehule