Backport criteria

I've been going through the ChangeLog for the release and am having trouble justifying some of the changes brought in. In particular: * -fstrict-volatile-bitfields, which is more appropriate for bare metal/kernel code * Cortex-M4 support * C locale support in libstdc++-v3

The march/mcpu clean up is OK but marginal.

Our focus is time based performance on the Cortex-A series with an implied applications over kernel/bare metal. This is a very narrow view, but every non-performance line of code we bring in can also bring in a bug.

Any thoughts? For those who are looking at using our toolchain, is earlier access to other toolchain improvements interesting?

-- Michael