include/my_pthread.h:
  Fix for Bug#27970 "Fix for bug 24507 makes mysql_install_db fail".
  
  Removed macro NPTL_PTHREAD_EXIT_BUG, because it doesn't work in dynamic
  environment. One can switch between NPTL and LT on the fly on Linux.
  
  Added pthread_dummy(ESRCH) for those platforms that don't have pthread_kill.
  This ensures that there won't be an error in mysqld.cc where the return value 
  is being checked from the function call.
mysys/my_thr_init.c:
  Check for a Linux is enough. There is an additional test if
  NPTL is in use before spwaning the extra thread.