Minor conditionals to enable building Scheduler Simulator on GNU/Linux

- rtems/score/assert.h: Scheduler Simulator uses glibc assert.h on GNU/Linux.
  This will likely need to be adjusted more for other host compilers and
  C libraries. Also disable _Assert_Not_reached() because some of these
  paths do actually return to the called on the Scheduler Simulator.

- basedefs.h: Do not use noreturn attribute when on Scheduler Simulator.
  Paths which context switch can return to the command interpreter on
  the Scheduler Simulator.
cpusetimpl.h: Add _CPU_set_Set() and improve Doxygen
m68k/shared/misc/memProbe.c: Add prototype to eliminate warning
mrm332: Tests now build and fewer warnings
rtems: Coding style
score: _Scheduler_Get_affinity()

Drop scheduler parameter.  Coding style.
score: _Scheduler_Set_affinity()

Do not change the scheduler with this function.  Documentation.  Coding
style.
libblock: Use pthread_once() for initialization

Enabling and disabling preemption as done for single core will not work
for SMP.  In the bdbuf initialization preemption handling can be avoided
in general by using pthread_once().
arm: Add ARM_MULTILIB_HAS_BARRIER_INSTRUCTIONS
rtems: Avoid copy and paste in confdefs.h

Add and use CONFIGURE_POSIX_MUTEXES.
Add and use CONFIGURE_POSIX_CONDITION_VARIABLES.
libblock: Add RTEMS_BDBUF_USE_PTHREAD

Use the PTHREAD mutexes and condition variables if available.  This
helps on SMP configurations to avoid the home grown condition variables
via disabled preemption.
score: Add Resource Handler

A resource is something that has at most one owner at a time and may
have multiple rivals in case an owner is present.  The owner and rivals
are impersonated via resource nodes.  A resource is represented via the
resource control structure.  The resource controls and nodes are
organized as trees.  It is possible to detect deadlocks via such a
resource tree.  The _Resource_Iterate() function can be used to iterate
through such a resource tree starting at a top node.
score: Add and use _Thread_Owns_resources()
score: Add resource node to thread control block
score: Use Resource Handler for MrsP semaphores

This enables proper resource dependency tracking and as a side-effect
deadlock detection.
smptests/smpmrsp01: Fix scheduler ids
smptests/smpthreadlife01: Fix for debug enabled
libblock: Avoid recursive mutex
score/sparc: Add support for paravirtualization

Guest systems in paravirtualization environments run usually in user
mode.  Thus it is not possible to directly access the PSR and TBR
registers.  Use functions instead of inline assembler to access these
registers if RTEMS_PARAVIRT is defined.
rhealstone: Produce proper begin/end messages