avcodec/vc1: implement interlaced out-of-bounds reference pixel replication

The existing implementation did out-of-bounds reference pixel replication for
progressive reference frames. In interlaced reference frames both the even and
odd line on the horizontal edges need to be replicated.

Fixes #3262.
Signed-off-by: Jerome Borsboom <jerome.borsboom@carpalis.nl>

tests/ref/fate/vc1_ilaced_twomv

@@ -7,12 +7,12 @@
 0,          2,          2,        1,  3110400, 0x3b615b79
 0,          3,          3,        1,  3110400, 0x4fbb6f84
 0,          4,          4,        1,  3110400, 0xc1ca8532
-0,          5,          5,        1,  3110400, 0xb6e7d363
-0,          6,          6,        1,  3110400, 0x1beb5c34
-0,          7,          7,        1,  3110400, 0xcb8cb061
-0,          8,          8,        1,  3110400, 0x13ddbd61
-0,          9,          9,        1,  3110400, 0xde8f052f
-0,         10,         10,        1,  3110400, 0x4d4072db
-0,         11,         11,        1,  3110400, 0x4e5d29e3
-0,         12,         12,        1,  3110400, 0x75300531
-0,         13,         13,        1,  3110400, 0x1114285a
+0,          5,          5,        1,  3110400, 0xbdabd2a8
+0,          6,          6,        1,  3110400, 0x66e60c5a
+0,          7,          7,        1,  3110400, 0x8044891c
+0,          8,          8,        1,  3110400, 0x3a4e8992
+0,          9,          9,        1,  3110400, 0xe49fcb23
+0,         10,         10,        1,  3110400, 0xe8e165b6
+0,         11,         11,        1,  3110400, 0x046321b5
+0,         12,         12,        1,  3110400, 0x3cbe5125
+0,         13,         13,        1,  3110400, 0xcb4328e7