Add time namespace constant

This constant is a possible bitflag argument for `unshare`:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/sched.h?h=v6.6-rc1#n44

I am unsure about its support in Fuchsia, which is why I have not added
the constant there.

Author: cd-work

libc-test/semver/linux-gnu.txt

@@ -31,6 +31,7 @@ BPF_FS_MAGIC
 BTRFS_SUPER_MAGIC
 CGROUP2_SUPER_MAGIC
 CGROUP_SUPER_MAGIC
+CLONE_NEWTIME
 CODA_SUPER_MAGIC
 CRAMFS_MAGIC
 DEAD_PROCESS

src/unix/linux_like/linux/gnu/mod.rs

@@ -944,6 +944,9 @@ pub const NT_PRFPXREG: ::c_int = 20;
 
 pub const ELFOSABI_ARM_AEABI: u8 = 64;
 
+// linux/sched.h
+pub const CLONE_NEWTIME: ::c_int = 0x80;
+
 // linux/keyctl.h
 pub const KEYCTL_DH_COMPUTE: u32 = 23;
 pub const KEYCTL_PKEY_QUERY: u32 = 24;