Add op_fclose to keep fclose's type signature the same

[oskarwirga]

This problem cropped up when I was trying to enable CFI-icall with Opusfile as a dependency. CFI indirect function call sanitization checks that function signatures at runtime match those that were determined at compile time. This fix ensures that fclose has the correct function signature when being passed a stream.

I have a quick sample here on Godbolt: https://godbolt.org/z/EGsPYae51

An exit code of 132 is SIGILL which means a CFI violation was found and program execution was stopped.