[NaCl SDK] nacl_io: Fix gaping memory leaks in memfs and htmlfs

[NaCl SDK] nacl_io: Fix gaping memory leaks in memfs and htmlfs

I introduced these leaks recently and really should
have run valgrind.  In future out valgrind bot should
find such things pre-submit.

Committed: https://crrev.com/67c19dd9512866cf31bae844300cf86f19338a0c
Cr-Commit-Position: refs/heads/master@{#296606}

[Sam Clegg, 2014-09-24 23:35:12]

sbc@chromium.org changed reviewers:
+ binji@chromium.org

[binji, 2014-09-24 23:58:11]

yikes, lgtm

[Sam Clegg, 2014-09-25 00:00:37]

The CQ bit was checked by sbc@chromium.org

[commit-bot: I haz the power, 2014-09-25 00:02:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/605433003/1

[commit-bot: I haz the power, 2014-09-25 01:11:21]

Committed patchset #1 (id:1) as ff5165d96612232464a7ae9dee452b9642fe1b67

[commit-bot: I haz the power, 2014-09-25 01:11:55]

Patchset 1 (id:??) landed as
https://crrev.com/67c19dd9512866cf31bae844300cf86f19338a0c
Cr-Commit-Position: refs/heads/master@{#296606}