Summary:
Bypass quarantine altogether when quarantine size is set ot zero.
Also, relax atomic load/store of quarantine parameters, the
release/acquire semantics is an overkill here.
Reviewers: eugenis
Subscribers: kubabrecka, llvm-commits, mehdi_amini
Differential Revision: https://reviews.llvm.org/D28586
llvm-svn: 291791