Fix in place huge reallocation to update the chunk counters that are
used for triggering gdump profiles.

Fix xallocx(..., MALLOCX_ZERO to zero the last full trailing page of
large allocations that have been randomly assigned an offset of 0 when
--enable-cache-oblivious configure option is enabled.  This addresses a
special case missed in d260f442 (Fix
xallocx(..., MALLOCX_ZERO) bugs.).

Work around a potentially bad thread-specific data initialization
interaction with NPTL (glibc's pthreads implementation).

This resolves #283.

Zero all trailing bytes of large allocations when
--enable-cache-oblivious configure option is enabled.  This regression
was introduced by 8a03cf03 (Implement
cache index randomization for large allocations.).

Zero trailing bytes of huge allocations when resizing from/to a size
class that is not a multiple of the chunk size.

Fix prof_tctx_dump_iter() to filter out nodes that were created after
heap profile dumping started.  Prior to this fix, spurious entries with
arbitrary object/byte counts could appear in heap profiles, which
resulted in jeprof inaccuracies or failures.

Fix prof_alloc_rollback() to read tdata from thread-specific data rather
than dereferencing a potentially invalid tctx.

Fix irallocx_prof_sample() to always allocate large regions, even when
alignment is non-zero.

Fix ixallocx_prof_sample() to never modify nor create sampled small
allocations.  xallocx() is in general incapable of moving small
allocations, so this fix removes buggy code without loss of generality.

Fix prof_realloc() to call prof_free_sampled_object() after calling
prof_malloc_sample_object().  Prior to this fix, if tctx and old_tctx
were the same, the tctx could have been prematurely destroyed.

Fix ixallocx_prof() to pass usize_max and zero to ixallocx_prof_sample()
in the correct order.

Make one call to prof_active_get_unlocked() per allocation event, and
use the result throughout the relevant functions that handle an
allocation event.  Also add a missing check in prof_realloc().  These
fixes protect allocation events against concurrent prof_active changes.

Fix xallocx() bugs related to the 'extra' parameter when specified as
non-zero.

Fix heap profiling to distinguish among otherwise identical sample sites
with interposed resets (triggered via the "prof.reset" mallctl).  This
bug could cause data structure corruption that would most likely result
in a segfault.

Fix TLS configuration such that it is enabled by default for platforms
on which it works correctly.  This regression was introduced by
ac5db020 (Make --enable-tls and
--enable-lazy-lock take precedence over configure.ac-hardcoded
defaults).

Fix chunk purge hook calls for in-place huge shrinking reallocation to
specify the old chunk size rather than the new chunk size.  This bug
caused no correctness issues for the default chunk purge function, but
was visible to custom functions set via the "arena.<i>.chunk_hooks"
mallctl.

This resolves #264.

Fix arenas_cache_cleanup() and arena_get_hard() to handle
allocation/deallocation within the application's thread-specific data
cleanup functions even after arenas_cache is torn down.

This is a more general fix that complements
45e9f66c (Fix arenas_cache_cleanup().).

Add JEMALLOC_CXX_THROW to the memalign() function prototype, in order to
match glibc and avoid compilation errors when including both
jemalloc/jemalloc.h and malloc.h in C++ code.

This change was unintentionally omitted from
ae93d6bf (Avoid function prototype
incompatibilities.).