Decrease the Series_Memory when the series is freed
Decrease the Series_Memory when the series is freed

Or this stat doesn't make much sense. With this change, it now refers to
the series memory that's in use.

draegtun/ren-c,hostilefork/rebol,mbk/ren-c,kealist/ren-c,hostilefork/rebol,kealist/ren-c,giuliolunati/ren-c,rgchris/ren-c,mbk/ren-c,codebybrett/ren-c,kealist/ren-c,giuliolunati/ren-c,hostilefork/rebol,giuliolunati/ren-c,mbk/ren-c,kealist/ren-c,draegtun/ren-c,rgchris/ren-c,giuliolunati/ren-c,rgchris/ren-c,codebybrett/ren-c,hostilefork/rebol,codebybrett/ren-c,codebybrett/ren-c,codebybrett/ren-c,mbk/ren-c,hostilefork/rebol,draegtun/ren-c,kealist/ren-c,codebybrett/ren-c,draegtun/ren-c,rgchris/ren-c,kealist/ren-c,draegtun/ren-c,hostilefork/rebol,draegtun/ren-c,rgchris/ren-c,giuliolunati/ren-c