-Werror,-Wunused-macros

<https://msdn.microsoft.com/en-us/library/windows/desktop/ms647466%28v=vs.85%29.aspx>
"About Strsafe.h":

  When you include Strsafe.h in your file, the older functions replaced by the
  Strsafe.h functions will be deprecated. Attempts to use these older functions
  will result in a compiler error telling you to use the newer functions. If you
  want to override this behavior, include the following statement before
  including Strsafe.h.

  #define STRSAFE_NO_DEPRECATE

Appears to no (longer?) be relevant here, as reported by clang-cl.

Change-Id: I94a576b71a2a34edd6009059fc5047ba59ec0f12

avmedia/source/win/window.cxx

@@ -24,7 +24,6 @@
 #include <objbase.h>
 #include <strmif.h>
 #include <control.h>
-#define STRSAFE_NO_DEPRECATE
 #include <dshow.h>
 #if defined _MSC_VER
 #pragma warning(pop)