Move MemoryRegionInfo out of Target/Process.h into its own header.

lldb-gdbserver and NativeProcessProtocol will use MemoryRegionInfo
but don't want to pull in Process.h.  Pull this declaration and
definition out into its own header.


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@210213 91177308-0d34-0410-b5e6-96231b3b80d8