kmscube - meson - required version is 0.47, but the 'break' keyword in a for_each loop actually requires 0.49

I was trying to build kmscube to test something on a gentoo box that hasn't yet managed to get X up and running. Meson 0.48.2 was installed, but I couldn't build w/ meson due to the break keyword being used in a for_each loop which was first supported in 0.49.

Either rewrite the foreach/break, or just bump the minimum meson version.