Try harder to be signal-safe inside our signal handler. The most prominent behavioural
difference is that we no longer clean the token before emitting it. This fixes a bug where
clang hangs in the middle of crashing because the crash handler calls malloc from inside
a crash that happened inside of free.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@177919 91177308-0d34-0410-b5e6-96231b3b80d8