Quick compiler, out of registers fix

Fixes b/15024623

It turns out that the register pool sanity checker was not
working as expected, leaving some inconsistencies unreported.
This CL fixes the sanity checker, adds a lot more check and cleans
up the previously undetected episodes of insanity.

Change-Id: I4d67db864ca5926a1975db251e7e631b65a86275
17 files changed