This patch imports the initial state of asan as it was in the
Google branch.
It provides basic infrastructure for asan to instrument memory
accesses on the heap, at -O3. Note that it supports neither stack nor
global variable protection.
The rest of the patches of the set is intended to further improve this
base.
* Makefile.in: Add asan.c and its dependencies.
* common.opt: Add -fasan option.
* invoke.texi: Document the new flag.
* passes.c: Add the asan pass.
* toplev.c (compile_file): Call asan_finish_file.
* asan.c: New file.
* asan.h: New file.
* tree-pass.h: Declare pass_asan.