Avoid using malloc debug code after exit.

I wrote a new unit test that would fail on the old version of the
code.

On a walleye big cpu, this costs about 40ns-50ns (going from ~430ns to ~480ns).
I think this is an acceptable performance degradation.

Bug: 131867816

Test: New unit tests pass.
Change-Id: I4c0f4373fb0694bf29c3824dbb1224a8a17e211e
Merged-In: I4c0f4373fb0694bf29c3824dbb1224a8a17e211e
(cherry picked from commit d269fcc935b276502b9e47a575d76693fe1b8455)