Provide a placement new definition for the SEH version of UnwindCursor

This fixes compilation after SVN r352966 in SEH mode.

git-svn-id: https://llvm.org/svn/llvm-project/libunwind/trunk@353010 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/UnwindCursor.hpp b/src/UnwindCursor.hpp
index 406f229..836de38 100644
--- a/src/UnwindCursor.hpp
+++ b/src/UnwindCursor.hpp
@@ -482,6 +482,10 @@
   DISPATCHER_CONTEXT *getDispatcherContext() { return &_dispContext; }
   void setDispatcherContext(DISPATCHER_CONTEXT *disp) { _dispContext = *disp; }
 
+  // libunwind does not and should not depend on C++ library which means that we
+  // need our own defition of inline placement new.
+  static void *operator new(size_t, UnwindCursor<A, R> *p) { return p; }
+
 private:
 
   pint_t getLastPC() const { return _dispContext.ControlPc; }