move /data/tombstone creation to system/core

move /data/tombstones creation to system/core. In addition,
move the creation of /data/tombstones/mdm to the "on post-fs-data"
section of init.hammerhead.rc. /data isn't guaranteed to be
mounted during "on boot", only after "on post-fs-data"

Bug: https://code.google.com/p/android/issues/detail?id=93207
Change-Id: If397deb56074b7b4b04ae084da372a04c55a7e72
1 file changed