Build on Windows

[rinon]

We need to make sure that rav1d builds for windows, ideally with cargo to make things easy. We currently require nasm, but pass ELF-specific arguments which fails to build on Windows.

[thedataking]

Task breakdown

• use fseek instead of fseeko
• stdin and stderr as functions
• clock_gettime
• update build.rs for assembly support
• figure out how to reliably link against oldnames.lib
• cleanup
• Build in CI
• Run tests in CI

Status: successfully ran .\target\release\dav1d.exe -i Chimera-AV1-8bit-1920x1080-6736kbps.ivf -o /dev/null --threads 8 PR has some rough edges and decoding speed seems wrong:

dav1d 966d63c1 - by VideoLAN
Decoded 8929/8929 frames (100.0%) - 104.11/1784.02 fps (0.06x)