[DO-971] ffmpeg recipe with requirements (!9)

Co-authored-by: aleksandr.vodyanov <aleksandr.vodyanov@avroid.tech>
Reviewed-on: https://git.avroid.tech/Conan/conan_build/pulls/9

recipes/opus/all/test_package/test_package.c

@@ -0,0 +1,13 @@
+#include <stdio.h>
+#include <opus/opus.h>
+
+int main() {
+    int err;
+    int rate = 48000;
+    int channels = 2;
+    int application = OPUS_APPLICATION_AUDIO;
+    OpusEncoder *encoder;
+
+    encoder = opus_encoder_create(rate, channels, application, &err);
+    opus_encoder_destroy(encoder);
+}