Add valgrind tests

Author: palemieux

imf-unit-tests.sh

@@ -1,4 +1,7 @@
 #!/bin/sh
 
+valgrind --leak-check=full ./ffmpeg -y -i http://ffmpeg-imf-samples-public.s3.us-west-1.amazonaws.com/callout_51_l_r_c_lfe_ls_rs.mxf -f wav /dev/null
+valgrind --leak-check=full ./ffmpeg -y -i http://ffmpeg-imf-samples-public.s3-website-us-west-1.amazonaws.com/countdown/CPL_f5095caa-f204-4e1c-8a84-7af48c7ae16b.xml -f mp4 /dev/null
+
 make libavformat/tests/imf
-valgrind --leak-check=full libavformat/tests/imf
+valgrind --leak-check=full libavformat/tests/imf