gcc: Add 4.9 recipes

Signed-off-by: Khem Raj <raj.khem@gmail.com>
tcmode-default.inc: Default to using gcc 4.9

Signed-off-by: Khem Raj <raj.khem@gmail.com>
systemd: Fix build with gcc 4.9

We need to use gcc-nm and gcc-ar to deal with slim objects
which are generated when using -flto

Signed-off-by: Khem Raj <raj.khem@gmail.com>