Remove task-private memory allocation.

[Reviewed by sungeun.]

The hierarchical locales branch merge added a per-task memory allocation
interface, implemented by calling through task-private function pointers
to routines to do malloc(), calloc(), realloc(), and free().  However,
we can achieve the same localized allocation capability without the
overhead of the indirect call, using chpl_here_alloc() and its peers.
(For allocations elsewhere we'll need something like chpl_there_alloc(),
in the future.)

In the meantime, here we actually call the chpl_mem_*() routines instead
of the chpl_here_*() ones, because the latter are currently coded to be
generic in their first parameter and return value, and some of the calls
we are replacing are after resolution, too late to get the types right.
We'll fix this after we fix the chpl_here_alloc() interface.

Note that this still leaves the allocation function pointers in the task
private data.  A future cleanup commit will fix that in all the tasking
layers.

The specific file changes are as follows.

compiler/include/primitive.h
compiler/AST/primitive.cpp
  Remove PRIM_TASK_{ALLOC,REALLOC,FREE,MEMHOOK_FREE}.

compiler/include/expr.h
compiler/AST/expr.cpp
  Remove PRIM_TASK_{ALLOC,REALLOC,FREE,MEMHOOK_FREE}.
  Rename callTaskAlloc() to be callChplHereAlloc(), and add a matching
  callChplHereFree().  These callChplHere*() functions actually generate
  calls to the corresponding chpl_mem_*() functions.  We'll make them
  call chpl_here_*() later.

compiler/AST/checkAST.cpp
compiler/optimizations/scalarReplace.cpp
compiler/optimizations/optimizeOnClauses.cpp
  Remove PRIM_TASK_{ALLOC,REALLOC,FREE,MEMHOOK_FREE}.

compiler/passes/parallel.cpp
compiler/resolution/lowerIterators.cpp
compiler/resolution/callDestructors.cpp
  Replace calls to callTaskAlloc() with calls to callChplHereAlloc().
  Replace explicit PRIM_{TASK,CHPL}_FREE calls with callChplHereFree().
  Remove PRIM_CHPL_MEMHOOK_FREE invocations that are no longer needed.
  Remove comments that are no longer applicable.
  While here, remove some extraneous white space.

modules/internal/localeModels/flat/LocaleModel.chpl
  Replace task-private allocation calls with chpl_mem_*() equivalents,
  and adjust surrounding code and comments appropriately.

modules/internal/ChapelSyncvar.chpl
  Replace task-private allocation calls with chpl_mem_*() equivalents,
  and adjust surrounding code and comments appropriately.
  Reformat some comments to fit in fewer than 80 columns.

runtime/include/chpl-mem.h
  Add chpl_mem_calloc(), for convenience and symmetry.
  Recode slightly, allowing chpl_mem_realloc() and chpl_mem_free() to be
  declared in the same order as everywhere else: alloc, calloc, realloc,
  free.
  Remove chpl_tracked_task_{alloc,calloc,realloc,free}(), no longer
  used.

runtime/include/chpl-tasks.h
  Remove chpl_task_{alloc,calloc,realloc,free}(), no longer used.

runtime/include/qio/qbuffer.h
runtime/include/qio/deque.h
runtime/include/chpl-comm-compiler-macros.h
runtime/src/comm/none/comm-none.c
runtime/src/chpltypes.c
runtime/src/chplgmp.c
  Replace chpl_tracked_task_{alloc,calloc,realloc,free}() with the
  equivalent chpl_mem_{alloc,allocManyZero,realloc,free}().


git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@21838 3a8e244f-b0f2-452b-bcba-4c88e055c3ca
Added more segfaults for PGI on chpbld02 to REGRESSIONS.

They are in 'linux64.pgi.none.fifo.pthreads' configuration and started 9/7.

As Lydia explains, "These are old errors [...].  The original version
of thread-ring had them, so when I shifted and multiplied the
thread-ring test, these carried over, too."


git-svn-id: http://svn.code.sf.net/p/chapel/code/trunk@21839 3a8e244f-b0f2-452b-bcba-4c88e055c3ca