cmd/version: print os/version, kernel and bitness (#5204)

Related to #5121

Note: OpenBSD is stub yet. This will be fixed after upstream PR gets resolved
https://github.com/shirou/gopsutil/pull/993

lib/buildinfo/osversion.go

@@ -0,0 +1,34 @@
+// +build !openbsd,!windows
+
+package buildinfo
+
+import (
+	"strings"
+
+	"github.com/shirou/gopsutil/v3/host"
+)
+
+// GetOSVersion returns OS version, kernel and bitness
+func GetOSVersion() (osVersion, osKernel string) {
+	if platform, _, version, err := host.PlatformInformation(); err == nil && platform != "" {
+		osVersion = platform
+		if version != "" {
+			osVersion += " " + version
+		}
+	}
+
+	if version, err := host.KernelVersion(); err == nil && version != "" {
+		osKernel = version
+	}
+
+	if arch, err := host.KernelArch(); err == nil && arch != "" {
+		if strings.HasSuffix(arch, "64") && osVersion != "" {
+			osVersion += " (64 bit)"
+		}
+		if osKernel != "" {
+			osKernel += " (" + arch + ")"
+		}
+	}
+
+	return
+}