Resurrect <machine/_user_types.h> for use in <sys/types.h>. Newlib
targets may provide an own version of <machine/types.h> in their machine
directory to add custom user types for <sys/types.h>. Check the
_SYS_TYPES_H header guard to prevent a direct include of
<machine/types.h>, since the <machine/types.h> file is a Newlib
speciality.
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>
9bb91b6c6b