Newlib defines defaults for internal types via <sys/_types.h> and uses
<machine/_types.h> to let targets define their own type if necessary.
Previously for example
#ifndef __dev_t_defined
typedef short __dev_t;
#endif
However, the __*_t_defined pattern conflicts with the glibc type guard
pattern for user types, e.g. dev_t in this example. Introduce a
__machine_*_t_defined pattern for internal types (defined by
<machine/_types.h>, used by <sys/_types.h>). For example
#ifndef __machine_dev_t_defined
typedef short __dev_t;
#endif
Signed-off-by: Sebastian Huber <sebastian.huber@embedded-brains.de>