Add function to get process state on Unix.

process.go

@@ -19,6 +19,9 @@ type Process interface {
 	// Executable name running this process. This is not a path to the
 	// executable.
 	Executable() string
+
+	// State for this process. Returns zero on Darwin and Windows.
+	State() rune
 }
 
 // Processes returns all processes.

process_darwin.go

@@ -27,6 +27,10 @@ func (p *DarwinProcess) Executable() string {
 	return p.binary
 }
 
+func (p *DarwinProcess) State() rune {
+	return 0
+}
+
 func findProcess(pid int) (Process, error) {
 	ps, err := processes()
 	if err != nil {

process_freebsd.go

@@ -121,6 +121,10 @@ func (p *UnixProcess) PPid() int {
 	return p.ppid
 }
 
+func (p *UnixProcess) State() rune {
+	return p.state
+}
+
 func (p *UnixProcess) Executable() string {
 	return p.binary
 }

process_unix.go

@@ -29,6 +29,10 @@ func (p *UnixProcess) PPid() int {
 	return p.ppid
 }
 
+func (p *UnixProcess) State() rune {
+	return p.state
+}
+
 func (p *UnixProcess) Executable() string {
 	return p.binary
 }

process_windows.go

@@ -57,6 +57,10 @@ func (p *WindowsProcess) Executable() string {
 	return p.exe
 }
 
+func (p *WindowsProcess) State() rune {
+	return 0
+}
+
 func newWindowsProcess(e *PROCESSENTRY32) *WindowsProcess {
 	// Find when the string ends for decoding
 	end := 0