toolchain: add gcc 4.9 series

Add the recently released gcc 4.9.0.
Use 4.8.2 patches and remove those that no longer apply/are needed
(mostly PR fixes and xtensa).
libmudflap was removed upstream.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>