Update to v5.0 kernel headers.

Test: Builds and boots on taimen.
Change-Id: I13843bf1ab30ea89a50852adc88f2cba8401bded
diff --git a/libc/kernel/uapi/linux/btrfs.h b/libc/kernel/uapi/linux/btrfs.h
index 2bb79d8..0dae543 100644
--- a/libc/kernel/uapi/linux/btrfs.h
+++ b/libc/kernel/uapi/linux/btrfs.h
@@ -173,6 +173,7 @@
 #define BTRFS_FEATURE_INCOMPAT_RAID56 (1ULL << 7)
 #define BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA (1ULL << 8)
 #define BTRFS_FEATURE_INCOMPAT_NO_HOLES (1ULL << 9)
+#define BTRFS_FEATURE_INCOMPAT_METADATA_UUID (1ULL << 10)
 struct btrfs_ioctl_feature_flags {
   __u64 compat_flags;
   __u64 compat_ro_flags;