Trivial: Style fix

make the style checker happy

seL4_libs: remove autoconf.h from seL4_libs

this commit removes autoconf.h generation from each lib and
append '#include <<lib_name>/gen_config.h>' after each
'#include <autoconf.h>' since autoconf.h is only the for the
kernel config now. This is a temporarily solution, since we
currently don't have a way to tell which header files each file
is trying to include when it includes 'autoconf.h'

Fix all the whitespace

- remove trailing whitespace
- remove duplicate blank lines
- remove blank lines at end of files

Fix licenses

sel4utils: Check arm stack alignment with macro

sel4utils: Trivial whitespace

sel4utils: Add type for thread entry point

Our thread-starting code assumes that its entry point is a function.
Previously, a void pointer was used as the type of the entry point.
Now thread entry points must be pointers to functions with a signature
void (*)(void*, void*, void*).

Prepare for aarch64 implementation