Enable already existing rso regression test.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Signed-off-by: Justin Ruggles <justin.ruggles@gmail.com>

tests/ref/lavf/rso

@@ -0,0 +1,3 @@
+f41fd78f7df981802e7caeb23648b8c0 *./tests/data/lavf/lavf.rso
+45064 ./tests/data/lavf/lavf.rso
+./tests/data/lavf/lavf.rso CRC=0x74b2b546