mall 1.0.0 - glibc-specific extras!

New methods that map to glibc malloc_* extensions:

* Mall.trim        ->  malloc_trim()
* Mall.xml         ->  malloc_info()  (requires glibc 2.10+)
* Mall.dump_stats  ->  malloc_stats()

Mall::ARENA_MAX and Mall::ARENA_TEST are also glibc-specific
constants for Mall.opt.  With Mall.xml from glibc 2.10+, Mall
is ENTERPRISE READY!!!1