[ASan] Add ASan debugging API to get malloc/free stack traces and shadow memory mapping info

Reviewed at http://reviews.llvm.org/D4466




git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@213080 91177308-0d34-0410-b5e6-96231b3b80d8
Add FreeBSD support to the address sanitizer's null_deref.cc test case
Differential Revision: http://reviews.llvm.org/D4421


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@213130 91177308-0d34-0410-b5e6-96231b3b80d8