Remove legacy_stdio_definitions.lib dep with mingw

[vrabaud]

This fixes #1647

[fdintino]

It looks like the only library I actually needed was advapi32.lib. My build fails after these changes (action run here) with the error:

avif.lib(std-43ecf4bdbb5e1e31.std.221f24cf-cgu.0.rcgu.o) : error LNK2001: unresolved external symbol __imp_OpenProcessToken
avif.lib(std-43ecf4bdbb5e1e31.std.221f24cf-cgu.0.rcgu.o) : error LNK2001: unresolved external symbol __imp_SystemFunction036
build\lib.win-amd64-cpython-39\PIL\_avif.cp39-win_amd64.pyd : fatal error LNK1120: 2 unresolved externals

Both of those symbols are in advapi32. Was its inclusion causing issues?

[wantehchang]

Frankie: Sorry about that. The inclusion of advapi32.lib did not cause problems, but it didn't seem necessary for two reasons:

• We didn't need it before, and
• The "Check static link bundling" step in .github/workflows/ci-windows.yml still passes without it.

We will be happy to add it back. But do you know why the "Check static link bundling" step you added cannot detect this problem?

[fdintino]

Yes. I think this is actually a problem with the windows static library from the rav1e release; I am using that in my build script whereas here rav1e is being built locally. I'll investigate further and report back.

[wantehchang]

Frankie: Thanks. We will wait for your report. Also, it would be good to figure out how to make "Check static link bundling" step in .github/workflows/ci-windows.yml reproduce this linker error.