The service omp_get_thread_num() now returns -1 if thread is not part of the runtime yet; this query allows to determine either we need to call and admit_current_thread service or not; closes #1247

gcc-8 requires an alias function to have the same exact return type

The main WD should be implicit to honor the implicit parallel
of size 1 that executes the main program.

As a side effect, the main WD in OmpSs can no longer ignore the
barrier construct and must be explicitly prevented.

Only if compiled for DLB support, this function will register
the Nanos++ interface in DLB

* Remove DLB library versioning, only link agaist ldlb
* Remove DLB dependency on support lib
* Add DLB dependency on pms lib

They are changed by scoped namespaces.
Also normalized namespace definition.
See #1161

Needed for global library dependencies such as Hwloc.

Improved macro shell-compatibility.

Fixed several errors and corrected automake conditional variable names.

Allowing worksharing in OmpSs. Additionaly copy reduction must verify existant of parent task before calling copy reduction; closes #1098

Reduced configure complexity by moving MPI and arch dependent checks (e.g. MIC, BG/Q) to a m4 macro file.

Old ResourceManager features have been split into different derived
classes in ThreadManager.

The ThreadManager can be specified by a new user option
--thread-manager, which currently accepts 'basic', 'basic-dlb' and
'auto-dlb'. Default value is none

   * Devices can reserve CPUs, but SMP threads may ignore it
   * SMP threads no longer reserve CPUs
   * Fix infinite loop looking for available CPUs, fixes #1035
   * Fix race condition when two threads were calling Extrae to increase the number of threads

Splitting OpenMP/OmpSs pm libraries through conditional compilation; With this changes programmming model will be decided according with which of these two libraries is the application linked with

WORKAROUND for a deadlock problem in smpthread wait and corrected warning message about OMP_NUM_THREADS variable