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 licenses

libsel4muslcsys: Use verbose logging for output in some syscalls

The printing in these syscalls is sometimes informative, but frequently is just spam.

libsel4muslcsys: Add some missing thread routines

A C library may call set_thread_area on startup and tkill on shutdown,
so we need to implement stubs of these