update systrace implementation

turn on with ENABLE_SYSTRACE shell variable
use write syscall directly with ctypes

Signed-off-by: Young-Ho Cha <ganadist@gmail.com>
update CFLAGS for c library

add Os flag
add fPIC flag for using shared library

Signed-off-by: Young-Ho Cha <ganadist@gmail.com>
exit when got signal

Signed-off-by: Young-Ho Cha <ganadist@gmail.com>