Add support for __builtin_unwind_init.

Also, committing an #if 0'ed __builtin_setjmp and __builtin_longjmp 
implementation I've had sitting in my tree for a while.  I haven't 
enabled it because the LLVM backend support isn't complete yet.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72727 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/builtin-unwind-init.c b/test/CodeGen/builtin-unwind-init.c
new file mode 100644
index 0000000..49a016a
--- /dev/null
+++ b/test/CodeGen/builtin-unwind-init.c
@@ -0,0 +1,4 @@
+// RUN: clang-cc -emit-llvm < %s -o - | grep -F "llvm.eh.unwind.init"
+
+int a() { __builtin_unwind_init(); }
+