Revert "Revert "bootstat: Handle v1 record files which do not contain file contents.""

This reverts commit 756b6a53.

The change is updated to use utimes (instead of futimens) since only
support for seconds resolution is required.

Bug: 27836969
Change-Id: I7134f759fb643e1a149158fcf6e20f76538b57d3
(cherry picked from commit c0dc139b)