fuse: replace deprecated StringBytePtr with BytePtrFromString

[Stavrospanakakis]

As mentioned in the Go codebase, the method syscall.StringBytePtr is deprecated and has to be replaced with syscall.BytePtrFromString.

// StringBytePtr returns a pointer to a NUL-terminated array of bytes.
// If s contains a NUL byte this function panics instead of returning
// an error.
//
// Deprecated: Use [BytePtrFromString] instead.
func StringBytePtr(s string) *byte { return &StringByteSlice(s)[0] }

// BytePtrFromString returns a pointer to a NUL-terminated array of
// bytes containing the text of s. If s contains a NUL byte at any
// location, it returns (nil, [EINVAL]).
func BytePtrFromString(s string) (*byte, error) {
	a, err := ByteSliceFromString(s)
	if err != nil {
		return nil, err
	}
	return &a[0], nil
}

https://github.com/golang/go/blob/8a4b439ee6e0f5d41cb6ae30146b901f3c0ad4b7/src/syscall/syscall.go#L57-L73

This pull request replaces the deprecated method.

Change-Id: I31b52356438352829971c6b491d37fe09e088911

[hanwen]

can you upload to gerrithub? thanks. See CONTRIBUTING.

[Stavrospanakakis]

@hanwen Sure, I uploaded the code to gerrithub.
https://review.gerrithub.io/c/hanwen/go-fuse/+/1201253

[hanwen]

thanks! merged as 58e0d83