build: Add _Pragma macro to disable deprecated declaration warnings

configure

@@ -1319,6 +1319,7 @@ HAVE_LIST="
     nanosleep
     poll_h
     posix_memalign
+    pragma_deprecated
     rdtsc
     sched_getaffinity
     sdl
@@ -3393,6 +3394,11 @@ void foo(char * $restrict_keyword p);
 EOF
 done
 
+check_cc <<EOF && enable pragma_deprecated
+_Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
+_Pragma("GCC diagnostic warning \"-Wdeprecated-declarations\"")
+EOF
+
 check_cc <<EOF && enable attribute_packed
 struct { int x; } __attribute__((packed)) x;
 EOF

libavutil/internal.h

@@ -61,6 +61,14 @@
 #    define av_export
 #endif
 
+#if HAVE_PRAGMA_DEPRECATED
+#    define FF_DISABLE_DEPRECATION_WARNINGS _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
+#    define FF_ENABLE_DEPRECATION_WARNINGS  _Pragma("GCC diagnostic warning \"-Wdeprecated-declarations\"")
+#else
+#    define FF_DISABLE_DEPRECATION_WARNINGS
+#    define FF_ENABLE_DEPRECATION_WARNINGS
+#endif
+
 #ifndef INT_BIT
 #    define INT_BIT (CHAR_BIT * sizeof(int))
 #endif