Log Message:
sysutils/xcp: update to 0.12.4

 - Minor cleanup of error handling
 - Convert low-level file operations to rustix
 - Convert lseek to rustix
 - Re-add userspace fallback
 - Use libc errno const for fiemap unsupported case
 - Start splitting into mulitiple crates
 - Remove unused kernel-syscall feature flag
 - Release libfs v0.1.0, xcp v0.12.3
 - Add libfs version