Fix binlog corruption with incorrectly serialized blob size.

[filipnavara]

Contributes to fixing xamarin/xamarin-macios#18568

Context

PR #9022 introduced a bug which started incorrectly serializing blobs in .binlog format due to overlooked long vs. int bug (https://github.com/dotnet/msbuild/pull/9022/files#r1271468212).

Changes Made

Added a missing int cast to preserve the original .binlog file format.

Testing

Manually tested that the .binlog is fixed and readable by MSBuildLog viewer after this change.

Notes

[dalexsoto]

❤️

[ladipro]

@filipnavara @dalexsoto
I was asked about this PR privately so just wanted to acknowledge that it's being reviewed with priority as it appears to be addressing a recent regression. Thank you!

[KirillOsenkov]

Thanks so much for getting to the bottom of it!

[KirillOsenkov]

As a separate PR (no need to give Filip more work), I recommend that the MSBuild team adds a unit-test that would have caught this regression (unless it's hard for some reason).

[rainersigwald]

I expect to do it in this PR (but our team can do it--I'm not assigning Filip more work!)--because I expect that Tactics will ask the "do you have a regression test for this?" question when we take this tomorrow.

[MichalPavlik]

Sorry for the inconvenience. I created PR with test targeting 17.7. In the meantime, you can use ProjectImports=ZipFile parameter to avoid code that causes the corruption. In this case, the archive will be separate file on the disk.

#9065

[filipnavara]

Superseded by #9065. Thanks for swift action.