Fix rallocx() sampling code to not eagerly commit sampler update.

rallocx() for an alignment-constrained request may end up with a
smaller-than-worst-case size if in-place reallocation succeeds due to
serendipitous alignment.  In such cases, sampling may not happen.

Author: jasone

src/jemalloc.c

@@ -2222,7 +2222,7 @@ irallocx_prof(tsd_t *tsd, void *old_ptr, size_t old_usize, size_t size,
 
 	prof_active = prof_active_get_unlocked();
 	old_tctx = prof_tctx_get(tsd_tsdn(tsd), old_ptr);
-	tctx = prof_alloc_prep(tsd, *usize, prof_active, true);
+	tctx = prof_alloc_prep(tsd, *usize, prof_active, false);
 	if (unlikely((uintptr_t)tctx != (uintptr_t)1U)) {
 		p = irallocx_prof_sample(tsd, old_ptr, old_usize, *usize,
 		    alignment, zero, tcache, arena, tctx);
@@ -2231,7 +2231,7 @@ irallocx_prof(tsd_t *tsd, void *old_ptr, size_t old_usize, size_t size,
 		    tcache, arena);
 	}
 	if (unlikely(p == NULL)) {
-		prof_alloc_rollback(tsd, tctx, true);
+		prof_alloc_rollback(tsd, tctx, false);
 		return (NULL);
 	}
 
@@ -2246,7 +2246,7 @@ irallocx_prof(tsd_t *tsd, void *old_ptr, size_t old_usize, size_t size,
 		 */
 		*usize = isalloc(tsd_tsdn(tsd), p, config_prof);
 	}
-	prof_realloc(tsd, p, *usize, tctx, prof_active, true, old_ptr,
+	prof_realloc(tsd, p, *usize, tctx, prof_active, false, old_ptr,
 	    old_usize, old_tctx);
 
 	return (p);