gcc: bump 4.9.x series to version 4.9.1

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

MtH: Resolved conflict:	package/gcc/Config.in.host
gcc: Move MXU support patch to 4.9.1 dir
opendingux: GCW0: defconfig: Update to reflect new dependencies

SDL2 and modplug are now auto-selected (via Love?), but SDL_gfx
now has to be selected manually (no longer pulled in via gmenu2x).