Update all scripts and build system to call python3, given python2's
upcoming doom. Use sys.maxsize instead of sys.maxint in one script
(maxint does not exist in python3).
Added an "ignore" argument to the circular_includes script. This
allows the caller to specify files for the script to ignore when
it parses the source file. Rather than creating a special
ignore case for "kernel_all.c" in the script itself, the user
parses the file as an argument (plus others if needed). Updated
the kernels cmake file to reflect the change.
