[asan] Add vfork to the list of reasons for stack errors.

Until we figure out what to do with it, vfork can cause stack-based
false positives.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@328681 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed