update deprecation of MAP_ANON from core.sys.posix.sys.mman

- remove MAP_ANON for linux from core.sys.posix.sys.mman
  (has been deprecated since sep 2013)

- add platform specific headers for mman (OSX, FreeBSD, Solaris, Android)

- add deprecation for other OSes
Revert "update deprecation of MAP_ANON from core.sys.posix.sys.mman"

This reverts commit 51c34ee56db983b3e08dee911f07010f3d4cc4bc.