Display SRCREVS in build log
The SRCREVS file is part of the artifacts in order to have all infor- mation for a reproducible build. Since artifacts are deleted after a few weeks, the information is gone, though. The build log is persistent, so we display the SRCREVS file in the log now after generating it.
Change-Id: Ieff9334237169f6a4d272be84e187b03c6ad7093