Fix compiler warnings.

lib/pls/include/pls/internal/scheduling/root_master_task.h

@@ -36,7 +36,7 @@ namespace pls {
                     }
                 }
 
-                bool my_stealing(abstract_task *other_task) override {
+                bool my_stealing(abstract_task* /*other_task*/) override {
                     return false;
                 }
             };

lib/pls/include/pls/internal/scheduling/root_worker_task.h

@@ -22,7 +22,7 @@ namespace pls {
                     } while (!master_task_->finished());
                 }
 
-                bool my_stealing(abstract_task *other_task) override {
+                bool my_stealing(abstract_task* /*other_task*/) override {
                     return false;
                 }
             };

lib/pls/include/pls/internal/scheduling/scheduler.h

@@ -44,7 +44,7 @@ namespace pls {
                 base::barrier sync_barrier_;
                 bool terminated_;
             public:
-                scheduler(const unsigned int num_threads):
+                explicit scheduler(const unsigned int num_threads):
                     num_threads_{num_threads},
                     sync_barrier_{num_threads + 1},
                     terminated_{false} {