add ctor for worker class in thread_pool

lib/include/srslte/common/thread_pool.h

@@ -50,6 +50,7 @@ public:
   class worker : public thread
   {
   public:
+    worker();
     void setup(uint32_t id, thread_pool *parent, uint32_t prio=0, uint32_t mask = 255);
     void stop();
     uint32_t get_id();

lib/src/common/thread_pool.cc

@@ -36,6 +36,7 @@
 
 namespace srslte {
 
+thread_pool::worker::worker() : my_id(0), running(false), my_parent(NULL) {}
 
 void thread_pool::worker::setup(uint32_t id, thread_pool *parent, uint32_t prio, uint32_t mask)
 {