Duplicate recent tasks=fifo hierarchical locale changes for tasks=mta.
Duplicate recent tasks=fifo hierarchical locale changes for tasks=mta.

[Reviewed by Tom.]

This adjusts mta tasking for locale-aware memory allocation in the same
way that r21331 and r21345 did so for fifo tasking.  The specific
changes are:
  - Remove the locally defined chpl_task_private_data_t and use the one
    defined in runtime/include/chpl-tasks.h instead.
  - Initialize the task private data inline in chpl_task_init(), so
    that the code looks the same as in fifo and qthreads tasking.
  - Add an implementation of chpl_task_getPrivateData() which can work
    when called from non-tasks, since we need it before tasking is
    initialized.
  - Remove a TODO comment in chpl_task_callMain(), added in r21331.  The
    work to be done actually went into chpl_task_init(), which makes it
    available a lot earlier.
  - Adjust chpl_task_{get,set}{Serial,Here,LocaleID}() to use the new
    chpl_task_getPrivateData().


git-svn-id: 5aabc979e906cfa1cd4a03d781c193b99fe6e46f@21358 3a8e244f-b0f2-452b-bcba-4c88e055c3ca

hildeth/chapel,CoryMcCartan/chapel,chizarlicious/chapel,hildeth/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,hildeth/chapel,chizarlicious/chapel,hildeth/chapel,hildeth/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,hildeth/chapel,chizarlicious/chapel,chizarlicious/chapel,CoryMcCartan/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,CoryMcCartan/chapel,sungeunchoi/chapel,sungeunchoi/chapel,chizarlicious/chapel,chizarlicious/chapel,sungeunchoi/chapel,hildeth/chapel,sungeunchoi/chapel,chizarlicious/chapel