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'

sel4utils: helpers for setting 64bit values in mrs

Adds the following methods

- sel4utils_64_get_mr
- sel4utils_64_set_mr

for putting 64bit values into message registers on 32 and 64 bit
platforms.

trivial: use pragma once

Fix licenses

libsel4utils: Change include order for zf_log.h

sel4_zf_logif.h should be included after utils/util.h

Move sel4_debug.h back into libsel4utils

This patch also renames a header {sel4debug/sel4_debug.h=>sel4utils/strerror.h}.

Additionally, convert some header guards to #pragma once and update
README.md to describe what things should go into libsel4utils and
libsel4debug.

SELFOUR-513

sel4utils: make sel4_zf_logif a default include

Rationalise dependencies.

This commit removes the dependency of libsel4platsupport on
libsel4utils, as libsel4utils is our top level library and should be
able to use the device drivers that libsel4platsupport provides.

The functionality that libsel4platsupport depended on from libsel4utils
has been moved to libsel4simple, as libsel4simple is basically an
extension of libsel4.