replace kernel_autoconf with sel4_autoconf

since the mainline kernel's kernel_autoconf doesn't include
seL4/gen_config.h but sel4_autoconf does

link kernel_autoconf explicitly

explicitly link kernel_autoconf on each subdirectory

seL4_libs: specify linking method

this commit set as much private linked config as possible

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'

Add CMake build rules for various libraries