lavu/attributes: introduce AV_NOWARN_DEPRECATED.

libavutil/attributes.h

@@ -88,6 +88,24 @@
 #endif
 #endif
 
+/**
+ * Disable warnings about deprecated features
+ * This is useful for sections of code kept for backward compatibility and
+ * scheduled for removal.
+ */
+#ifndef AV_NOWARN_DEPRECATED
+#if AV_GCC_VERSION_AT_LEAST(4,6)
+#    define AV_NOWARN_DEPRECATED(code) \
+        _Pragma("GCC diagnostic push") \
+        _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"") \
+        code \
+        _Pragma("GCC diagnostic pop")
+#else
+#    define AV_NOWARN_DEPRECATED(code) code
+#endif
+#endif
+
+
 #ifndef av_unused
 #if defined(__GNUC__)
 #    define av_unused __attribute__((unused))