Removed alignas() in cxxabi code.
Removed alignas() in cxxabi code.

g++ < 4.8 does not implement alignas(). Replaced the one use of it with
__attribute__((aligned())) for now.  Needs revisiting if we switch to gcc 4.8
in blessed toolchain.

utsav2601/cmpe295A,BarrelfishOS/barrelfish,linusyang/barrelfish,linusyang/barrelfish,utsav2601/cmpe295A,linusyang/barrelfish,8l/barrelfish,kishoredbn/barrelfish,utsav2601/cmpe295A,BarrelfishOS/barrelfish,8l/barrelfish,utsav2601/cmpe295A,BarrelfishOS/barrelfish,mslovy/barrelfish,BarrelfishOS/barrelfish,kishoredbn/barrelfish,mslovy/barrelfish,mslovy/barrelfish,kishoredbn/barrelfish,mslovy/barrelfish,8l/barrelfish,utsav2601/cmpe295A,BarrelfishOS/barrelfish,mslovy/barrelfish,BarrelfishOS/barrelfish,8l/barrelfish,utsav2601/cmpe295A,BarrelfishOS/barrelfish,kishoredbn/barrelfish,linusyang/barrelfish,BarrelfishOS/barrelfish,mslovy/barrelfish,linusyang/barrelfish,BarrelfishOS/barrelfish,kishoredbn/barrelfish,8l/barrelfish,kishoredbn/barrelfish,8l/barrelfish