Summary:
With this change, the user may safely call __asan_get_ownership()
from malloc/free hooks and assume it would return "true". If there is a
realloc/free race, free hook might be called twice, but I think it's acceptable,
as it's a data race and would later be reported anyway.

This change also fixes a bug when failing realloc incorrectly marked the
original memory as "quarantinned".

Reviewers: timurrrr, kcc, samsonov

Reviewed By: samsonov

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D913

llvm-svn: 183220