up the msvc warning level on srtp

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@3099 d0543943-73ff-0310-b7d9-9358b9ac24b2

libs/srtp/crypto/cipher/null_cipher.c

@@ -48,6 +48,10 @@
 #include "null_cipher.h"
 #include "alloc.h"
 
+#ifdef _MSC_VER
+#pragma warning(disable:4100)
+#endif
+
 /* the null_cipher uses the cipher debug module  */
 
 extern debug_module_t mod_cipher;