Improve abort message in `SwapSpace::NewFileChunk()`.

Use `PLOG` to print the `errno` information. Replace the
"Aborting..." with a more descriptive message, repeating a
`LOG(ERROR)` which is usually often lost in crash reports.

Test: m
Bug: 193120528
Change-Id: Id3b4ca0f40d8c13de95825aeb0d83964435be91e
1 file changed