Several tests currently deadlock when the lit test suite is run on OS X. Let's mark them as unsupported.
Differential Revision: http://reviews.llvm.org/D14443
llvm-svn: 252402
signal handler reads sa_sigaction when a concurrent sigaction call can modify it
as the result in could try to call SIG_DFL or a partially overwritten function pointer
llvm-svn: 224530