MemoryIntArray: dup in writeToParcel.

Previously, if a MemoryIntArray is written to a parcel from multiple
threads, we'll create multiple ParcelFileDescriptors that own the same
file descriptor, which fdsan doesn't like. Instead of adopting and then
detaching, use ParcelFileDescriptor::fromFd which dups behind the scenes.

Bug: http://b/132720476
Test: treehugger
Change-Id: Iad4930cc2d8c59a9348fedb0889d24cb566afa62