[MinGW-dvlpr] Going forwards to gcc 4.9

[David G. <jdg...@ho...>]

What do we need to do to move towards a release of MinGW gcc 4.9?
Now that avys has reported a successful build of 4.9.1 and used it to
build binutils and gcc for ARM (with a few problems), gcc 4.9.1 looks
to be very close to being generally usable.