Remove obsolete types; add <inttypes.h> where needed; header fixes

Remove obsolete types; add <inttypes.h> where needed; header fixes

- Remove obsolete types like "uint32"; use "uint32_t" consistently.
- Make sure we include <inttypes.h> where needed.
- Header file guards should be FOO_H or SUBDIR_FOO_H; _FOO_H infringes
  on the C implementation's namespace and should only be used when
  writing libc!
- Change a few "int8_t" back to "char" where appropriate.  There are
  a lot more places where that should be done, though.
- Clean up the check for getuid/getgid in rdoff/rdlar.h.