std.compress.flate.Decompress: return correct size for unbuffered decompression

Closes #24686

As a bonus, this commit also makes the `git.zig` "testing `main`" compile again.
96be6f6566Ian Johnson committed on 8/5/2025, 2:32:14 AM· committed by Andrew Kelleyparent163e9ce
2 files changedLine totals unavailable