This finally enables full 64-bit obstack support. The glibc shared library
specific code is removed from obstack.c too, and the error handling code
conditionally compiled under control of another macro,
_OBSTACK_NO_ERROR_HANDLER.
* lib/obstack.h: Include string.h earlier.
(_OBSTACK_INTERFACE_VERSION): Define.
(_OBSTACK_SIZE_T, _CHUNK_SIZE_T): Define as size_t for version 2.
* lib/obstack.c: Don't include shlib-compat.h.
(OBSTACK_INTERFACE_VERSION): Delete.
(_OBSTACK_ELIDE_CODE): Rename from ELIDE_CODE. Define when version 1
glibc code is compatible with version 2. Don't include stdio.h for
__GNU_LIBRARY.
(obstack_exit_failure, print_and_abort, obstack_alloc_failed_handler):
Omit when _OBSTACK_NO_ERROR_HANDLER defined. Include stdio.h here.
(_obstack_compat, _obstack, _obstack_newchunk, obstack_free): Delete
glibc shared library specific source.