proc: Add process state T

On linux kernel 2.6.x, the Trace/Stop status is 'T'

Fixes #209

proc/proc_linux.go

@@ -27,6 +27,9 @@ const (
 	StatusRunning   = 'R'
 	StatusTraceStop = 't'
 	StatusZombie    = 'Z'
+  
+	// Kernel 2.6 has TraceStop as T
+	StatusTraceStopT = 'T'
 )
 
 // OSProcessDetails contains Linux specific

proc/threads_linux.go

@@ -30,7 +30,7 @@ func (t *Thread) halt() (err error) {
 
 func (t *Thread) stopped() bool {
 	state := status(t.ID, t.dbp.os.comm)
-	return state == StatusTraceStop
+	return state == StatusTraceStop || state == StatusTraceStopT
 }
 
 func (t *Thread) resume() error {