Merge branch 'master' into CRTP

diff --cc include/simgrid/s4u/Exec.hpp
index bf9acf3,989aa69..1e9de25
--- 1/include/simgrid/s4u/Exec.hpp
--- 2/include/simgrid/s4u/Exec.hpp
+++ b/include/simgrid/s4u/Exec.hpp
@@@ -25,8 -26,8 +25,7 @@@ class XBT_PUBLIC Exec : public Activity
    double priority_              = 1.0;
    double bound_                 = 0.0;
    double timeout_               = 0.0;
 -  std::string tracing_category_ = "";
    std::atomic_int_fast32_t refcount_{0};
-   Host* host_ = nullptr;
  
  protected:
    Exec();

diff --cc src/s4u/s4u_Exec.cpp
Simple merge