pseudo: use bbnote/bbwarn instead of echo

In the future bbnote/bbwarn will be integrated into bitbake's logging, so use
those functions instead of echo directly.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
pseudo: warn twice if the 32-bit toolchain appears broken

Putting a warning at the top of do_compile is useful but not everyone reads the
file from beginning to end, so use a trap to put the message at the bottom too.

[ YOCTO #4919 ]

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>