Using the standard gnulib obstack source requires importing quite a
lot of other files from gnulib, and requires build changes.
include/
PR gdb/17133
* obstack.h (__attribute_pure__): Expand _GL_ATTRIBUTE_PURE.
libiberty/
PR gdb/17133
* obstack.c (__alignof__): Expand alignof_type from alignof.h.
(obstack_exit_failure): Don't use exitfail.h.
(_): Include libintl.h when HAVE_LIBINTL_H and nls enabled.
Provide default. Don't include gettext.h.
(_Noreturn): Define.
* obstacks.texi: Adjust node references to external libc info files.
This copies obstack.[ch] from gnulib, and updates the docs. The next
patch should be applied if someone repeats the import at a later date.
include/
PR gdb/17133
* obstack.h: Import current gnulib file.
libiberty/
PR gdb/17133
* obstack.c: Import current gnulib file.
* obstacks.texi: Updated doc, from glibc's manual/memory.texi.
