Imports of package metrics

PathSynopsis
internal/godebugsPackage godebugs provides a table of known GODEBUG settings, for use by a variety of other packages, including internal/godebug, runtime, runtime/metrics, and cmd/go/internal/load.
mathPackage math provides basic constants and mathematical functions.
runtimePackage runtime contains operations that interact with Go's runtime system, such as functions to control goroutines.
unsafePackage unsafe contains operations that step around the type safety of Go programs.