Stop building RTTI information for *most* llvm libraries. Notable

missing ones are libsupport, libsystem and libvmcore.  libvmcore is
currently blocked on bugpoint, which uses EH.  Once it stops using
EH, we can switch it off.

This #if 0's out 3 unit tests, because gtest requires RTTI information.
Suggestions welcome on how to fix this.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94164 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm-c/Core.h

@@ -1007,7 +1007,7 @@ namespace llvm {
                                                         \
     template<typename T>                                \
     inline T *unwrap(ref P) {                           \
-      T *Q = dynamic_cast<T*>(unwrap(P));               \
+      T *Q = (T*)unwrap(P);                             \
       assert(Q && "Invalid cast!");                     \
       return Q;                                         \
     }