tsan: relax checking of errno spoiling in signal handlers
allow SIGABRT to spoil errno, because some real programs
reset SIGABRT handler in the handler, re-raise SIGABRT and return from the handler



git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@200304 91177308-0d34-0410-b5e6-96231b3b80d8