u_int8_t, etc are non-standard, so define on all platforms
Use uint32_t on ARM, not non-standard __uint32_t
Removed some uses of sys/types.h

It's useful to be able to compile openlibm in environments where this
doesn't exist (e.g. OS kernels).
Merge pull request #68 from talex5/type_includes

[RFC] Don't use sys/types.h