9pfs: fail local_statfs() earlier

If we cannot open the given path, we can return right away instead of
passing -1 to fstatfs() and close(). This will make Coverity happy.

(Coverity issue CID1371729)

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Daniel P. berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

hw/9pfs/9p-local.c

@@ -1053,6 +1053,9 @@ static int local_statfs(FsContext *s, V9fsPath *fs_path, struct statfs *stbuf)
     int fd, ret;
 
     fd = local_open_nofollow(s, fs_path->data, O_RDONLY, 0);
+    if (fd == -1) {
+        return -1;
+    }
     ret = fstatfs(fd, stbuf);
     close_preserve_errno(fd);
     return ret;