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

jemalloc/jemalloc-cmake,jemalloc/jemalloc-cmake,jemalloc/jemalloc-cmake,jemalloc/jemalloc-cmake