Modify xallocx() tests that expect to expand in place to use a separate
arena.  This avoids the potential for interposed internal allocations
from e.g. heap profile sampling to disrupt the tests.

This resolves #286.

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.).

In addition to depending on map coalescing, the test depended on
munmap() being disabled so that chunk recycling would always succeed.

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

This resolves #283.

Make mallocx() OOM testing work correctly even on systems that can
allocate the majority of virtual address space in a single contiguous
region.

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.

Run integration tests with MALLOC_CONF="prof:true,prof_active:false" in
addition to MALLOC_CONF="prof:true".

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

Simplify imallocx_prof_sample() to always operate on usize rather than
sometimes using size.  This avoids redundant usize computations and
more closely fits the style adopted by i[rx]allocx_prof_sample() to fix
sampling bugs.

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.

Systems that do not support chunk split/merge cannot shrink/grow huge
allocations in place.

This resolves #257.

This resolves #274.

Don't assume Bourne shell is in /bin/sh when running size_classes.sh .

Consider __sparcv9 a synonym for __sparc64__ when defining LG_QUANTUM.

This resolves #275.

This change was intended as part of
8f57e3f1 (Remove check_stress from check
target's dependencies.).

Add arena_prof_tctx_reset() and use it instead of arena_prof_tctx_set()
when resetting the tctx pointer during reallocation, which happens
whenever an originally sampled reallocated object is not sampled during
reallocation.

This regression was introduced by
594c759f (Optimize
arena_prof_tctx_set().)

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 ixallocx_prof() to clamp the extra parameter if size+extra would
overflow HUGE_MAXCLASS.