Update regtest checksums after revision 6001dad6.

The string "FFmpeg" was replaced by "Libav" in metadata that
got encoded in file headers.

tests/ref/lavf/mxf

-785e38ddd2466046f30aa36399b8f8fa *./tests/data/lavf/lavf.mxf
+6e9bd63c5cadd7550ad313553ebf665f *./tests/data/lavf/lavf.mxf
 525881 ./tests/data/lavf/lavf.mxf
 ./tests/data/lavf/lavf.mxf CRC=0x4ace0849
-b3174e2db508564c1cce0b5e3c1bc1bd *./tests/data/lavf/lavf.mxf_d10
+e7168856f2b54c6272685967e707fb21 *./tests/data/lavf/lavf.mxf_d10
 5330989 ./tests/data/lavf/lavf.mxf_d10
 ./tests/data/lavf/lavf.mxf_d10 CRC=0xc3f4f92e

tests/ref/lavf/ts

-e8d609b8a5b5854a4485718434b287f7 *./tests/data/lavf/lavf.ts
+1cebaf8b13700a3360e0c32551e36646 *./tests/data/lavf/lavf.ts
 406644 ./tests/data/lavf/lavf.ts
 ./tests/data/lavf/lavf.ts CRC=0x133216c1