[asan] workaround for asan bug 189 (swapcontext followed by throw gets OOM kill). Also, disable swapcontext_test on non-x86. Fix lint

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@182456 91177308-0d34-0410-b5e6-96231b3b80d8