Import obstack.c and obstack.h

Extract libiberty/obstack.c, include/obstack.h and libiberty/COPYING.lib from
https://github.com/gcc-mirror/gcc/archive/refs/tags/releases/gcc-11.2.0.tar.gz.

Bug: 199322054
Test: none
Change-Id: Ia066f92ccd28234a91ac65d5bbe01e109a214aa3
3 files changed
tree: 4bf158aad52e1579720839f76306df099af3144e
  1. include/
  2. libiberty/