move chkstk.s from ntdll to rtl because _alloca_probe needs to be exported by ntoskrn...
drwxr-xr-x - irc
drwxr-xr-x - msvc6
drwxr-xr-x - os2
drwxr-xr-x - posix
drwxr-xr-x - reactos
drwxr-xr-x - rosapps