[Bug target/64149] -mno-lra bitrots, suggest to remove for GCC 5

[rearnsha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64149

--- Comment #2 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
Sounds sensible to me.  

We switched to LRA quite late in gcc-4.9, so keeping a way to switch back in
case of problems was pragmatic.  But we've been running with the new code now
for a year and not encountered any major issues that couldn't be fixed pretty
quickly.