Break out create_contiguous_mspace_with_base
This routine allows creating a contiguous mspace from raw mapped memory.
In turn, this will enable preallocation of the 3 heap spaces, which will help
remembered sets and zygote/app checks given pointer values.
Include stddef.h to make the size_t visible.  Resolves a simulator
build break caused by a use of ashmem.h in an environment without
size_t.
Eliminate the stdint.h include.  In retrospect, it seems that the
source of the aforementioned build breakage was then errant include of
this header when stddef.h was intended.  Nothing in this file uses any
of the symbols exported from stdint.h, only symbols from stddef.h.
Add a new method to export the extent of the break, akin to return
value of sbrk(0) in UNIX.  In terms of dlmalloc and our proprietary
contiguous mspace class, this is the highest address returned by its
morecore method.
Merge commit 'b99a099cad7066274b25de9d603e7ced37d20e19' into oxygen_4.3

* commit 'b99a099cad7066274b25de9d603e7ced37d20e19':
  Add a new method to export the extent of the break, akin to return value of sbrk(0) in UNIX.  In terms of dlmalloc and our proprietary contiguous mspace class, this is the highest address returned by its morecore method.
  Eliminate the stdint.h include.  In retrospect, it seems that the source of the aforementioned build breakage was then errant include of this header when stddef.h was intended.  Nothing in this file uses any of the symbols exported from stdint.h, only symbols from stddef.h.
  Include stddef.h to make the size_t visible.  Resolves a simulator build break caused by a use of ashmem.h in an environment without size_t.
  Break out create_contiguous_mspace_with_base This routine allows creating a contiguous mspace from raw mapped memory. In turn, this will enable preallocation of the 3 heap spaces, which will help remembered sets and zygote/app checks given pointer values.