make pkg/parsers support darwin and solaris

Signed-off-by: allencloud <allen.sun@daocloud.io>

parsers/kernel/kernel_unix.go

@@ -0,0 +1,34 @@
+// +build linux freebsd solaris
+
+// Package kernel provides helper function to get, parse and compare kernel
+// versions for different platforms.
+package kernel
+
+import (
+	"bytes"
+)
+
+// GetKernelVersion gets the current kernel version.
+func GetKernelVersion() (*VersionInfo, error) {
+	var (
+		err error
+	)
+
+	uts, err := uname()
+	if err != nil {
+		return nil, err
+	}
+
+	release := make([]byte, len(uts.Release))
+
+	i := 0
+	for _, c := range uts.Release {
+		release[i] = byte(c)
+		i++
+	}
+
+	// Remove the \x00 from the release for Atoi to parse correctly
+	release = release[:bytes.IndexByte(release, 0)]
+
+	return ParseRelease(string(release))
+}