After a long gestation period, here comes our custom version of malloc(3)

using mmap(2) instead of sbrk(2).
To make a long story short, using mmap(2) in malloc(3) allows us to draw
all the benefits from our mmap(2)'s randomization feature, closing the
effort we did for returning memory blocks from random addresses.
Tested for a long time by many, thanks to them.
Go for it ! deraadt@