This changes the CI build to store the git commit and date into package
internal/version instead of package main. Doing this essentially merges our
two ways of tracking the go-ethereum version into a single place, achieving
two objectives:
- Bad block reports, which use version.Info(), will now have the git commit
information even when geth is built in an environment such as
launchpad.net where git access is unavailable.
- For geth builds created by `go build ./cmd/geth` (i.e. not using `go run
build/ci.go install`), git information stored by the go tool is now used
in the p2p node name as well as in `geth version` and `geth
version-check`.
