If mremap(2) is available and supports MREMAP_FIXED, use it for huge
realloc().
Initialize rtree later during bootstrapping, so that --enable-debug
--enable-dss works.
Fix a minor swap_avail stats bug.
Replace the single-character run-time flags with key/value pairs, which
can be set via the malloc_conf global, /etc/malloc.conf, and the
MALLOC_CONF environment variable.
Replace the JEMALLOC_PROF_PREFIX environment variable with the
"opt.prof_prefix" option.
Replace umax2s() with u2s().
