* libc/include/machine/_default_types.h: New file, contains what
was previously in libc/include/machine/_types.h.
* libc/include/machine/_types.h: Now only includes
machine/_default_types.h.
* libc/include/sys/reent.h: Remove _fpos_t and _fpos64_t.
* libc/include/sys/_types.h: Move _fpos_t and _fpos64_t to here,
with conditional declarations.
* libc/machine/spu/machine/_types.h: New file, add SPU specific
typedefs for _fpos_t and _fpos64_t.