runtime/cgo: add .file directive to GNU assembly files
    
    Without it, at least on ARM64 with older BFD linker, it will
    include the file of the object file (which is of a temporary path)
    as a debug symbol into the binary, causing the build to be
    nondeterministic. Adding a .file directive makes it to create a
    STT_FILE symbol with deterministic input, and prevent the linker
    creating one using the temporary object file path.
    
    Fixes #57035.
    
    Change-Id: I3ab716b240f60f7a891af2f7e10b467df67d1f31
    Reviewed-on: https://go-review.googlesource.com/c/go/+/454838
    Reviewed-by: Bryan Mills <bcmills@google.com>
    TryBot-Result: Gopher Robot <gobot@golang.org>
    Run-TryBot: Cherry Mui <cherryyz@google.com>