Cleanup in preparation for better 64-bit host support.

Cleanup in preparation for better 64-bit host support.

* bfd-in.h (bfd_64_type):  Remove.
* libbfd.c (_do_getb64, _do_putb64):  Use bfd_vma, not bfd_64_type.

* bfd-in.h (bfd_size):  Remove.

* bfd-in.h (bfd_offset):  Remove, after fixing ld/ldlang.[ch].

* bfd-in.h (bfd_word):  Remove.
* reloc.c (reloc_howto_type):  Replace bfd_word with bfd_vma.

* bfd-in.h (rawdata_offset):  Remove.
* reloc.c (arelent):  Replace rawdata_offset with bfd_size_type.
(bfd_perform_relocation):  Lint.
(enum bfd_reloc_status):  Comment cleanup.