The `ubuntu-latest` runner has been migrated to Ubuntu 22.04, which doesn't have
all the same multilib packages as 20.04. Although we'll probably want to migrate
eventually, we should ship Nomad 1.4.3 with the same toolchain as we did
previously so that we're not introducing new issues.
These flags were not being used because GNUmakefile overwrites them with
another value. We also don't want to set `-s -w` since they remove
information that is important for production debug.
In other projects this variable is used to override the default `-dev`
prerelease that is set even if `VersionPrerelease` is empty, but in
Nomad this check is never actually done because this conditional in
`version/version.go` is always false:
```go
func GetVersion() *VersionInfo {
// ...
rel := VersionPrerelease
// ...
if GitDescribe == "" && rel == "" && VersionPrerelease != "" {
rel = "dev"
}
// ...
}
```
This seems like some leftover from a previous release process, but I
decided the leave the code as is.
