Replace chunk stats code that was missing locking; this fixes a race
condition that could corrupt chunk statistics.
Converting malloc_stats_print() to use mallctl*().
Add a missing semicolon in th DSS code.
Convert malloc_tcache_flush() to a mallctl.
Convert malloc_swap_enable() to a set of mallctl's.
Clean up whitespace.
Lock access of swap_avail when printing stats.
Use inttypes.h for portable printf() format specifiers, specifically for
uint64_t (PRIu64).
Change highchunks and curchunks stats from (unsigned long) to (size_t).
