Rearrange directory structure
*.s.* and adjust cases of filenames so that
source matches files. Use unix style paths is source files.
This matches the directory structure expected by tools and make rules allowing C source to be sensibly inserted into the directory structure and helps with with cross compiling.
Tested on BCM2835, BonusBin, Browse, BuildHost, Disc, IOMD32, OMAP3, OMAP4, OMAP5, PlingSystem, Titanium, Tungsten and iMx6 builds with no changes to build output except debug information and build log.