Define FUSE_SUPER_MAGIC for Linux

[jiangliu]

The definition of FUSE_SUPER_MAGIC is missing from file src/libc/unix/linux_like/linux/gnu/mod.rs .
According to https://man7.org/linux/man-pages/man2/fstatfs64.2.html, FUSE_SUPER_MAGIC should be "0x65735546".