oss-fuzz: add test case for use of uninitialized value in put_8tap_scaled_c

==1==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x5a2c04 in iclip /src/dav1d/include/common/intops.h:44:28
    #1 0x5a3ee1 in put_8tap_scaled_c /src/dav1d/src/mc_tmpl.c:0
    #2 0x597b07 in put_8tap_smooth_scaled_c /src/dav1d/src/mc_tmpl.c:330:1
    #3 0x5d71c7 in mc /src/dav1d/src/recon_tmpl.c:593:13
    #4 0x5cf67d in dav1d_recon_b_inter_8bpc /src/dav1d/src/recon_tmpl.c:1299:27
    #5 0x501f0f in decode_b /src/dav1d/src/decode.c:1827:17
    #6 0x4ccced in decode_sb /src/dav1d/src/decode.c:1961:17
    #7 0x4cd802 in decode_sb /src/dav1d/src/decode.c:2005:21
    #8 0x4cd802 in decode_sb /src/dav1d/src/decode.c:2005:21
    #9 0x4cd802 in decode_sb /src/dav1d/src/decode.c:2005:21
    #10 0x4c9833 in dav1d_decode_tile_sbrow /src/dav1d/src/decode.c:2469:13
    #11 0x4ad905 in dav1d_tile_task /src/dav1d/src/thread_task.c:125:25
    #12 0x49f1ae in __msan::MsanThread::ThreadStart() /src/llvm/projects/compiler-rt/lib/msan/msan_thread.cc:77