[Bug target/84882] -mstrict-align on aarch64 should not be RejectNegative

[sudi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84882

--- Comment #2 from sudi at gcc dot gnu.org ---
Proposed patch

https://gcc.gnu.org/ml/gcc-patches/2018-03/msg01439.html