PA_MEMPOOL_SLOT_SIZE incompatible with MAX_ALLOC_SIZE

[rdiez]

The hard-coded value of 64 MB for PA_MEMPOOL_SLOT_SIZE in pulsecore/memblock.c is bigger than the hard-coded value of 20 MB for MAX_ALLOC_SIZE in pulse/xmalloc.c

If the OS has no shared memory or the like, that triggers an assert in pa_xmalloc() when allocating the first chunk of the memory pool.

[lennart]

Thanks! Fixed in r8df5b2d