Add btrfs headers (#132)

Author: zhangyuannie

Cargo.toml

@@ -21,7 +21,7 @@ static_assertions = "1.1.0"
 libc = "0.2.100"
 
 [package.metadata.docs.rs]
-features = ["default", "bootparam", "ioctl", "netlink", "io_uring", "if_arp", "if_ether", "if_packet", "net", "prctl", "elf", "xdp", "mempolicy", "system", "loop_device"]
+features = ["default", "bootparam", "btrfs", "ioctl", "netlink", "io_uring", "if_arp", "if_ether", "if_packet", "net", "prctl", "elf", "xdp", "mempolicy", "system", "loop_device"]
 targets = ["x86_64-unknown-linux-gnu", "i686-unknown-linux-gnu"]
 
 [lints.rust.unexpected_cfgs]
@@ -33,6 +33,7 @@ check-cfg = [
 # The rest of this file is auto-generated!
 [features]
 bootparam = []
+btrfs = []
 errno = []
 general = []
 if_arp = []

gen/include/stddef.h

@@ -0,0 +1 @@
+#define offsetof(t, d) __builtin_offsetof(t, d)

gen/modules/btrfs.h

@@ -0,0 +1,2 @@
+#include <linux/btrfs.h>
+#include <linux/btrfs_tree.h>