add CLONE_NEWTIME to Linux/musl

(backport <rust-lang#4226>)
(cherry picked from commit d05754d)
(cherry picked from commit e5a8390)

[ squashed two commits for the backport - Trevor ]

Author: SteveLauC

libc-test/semver/linux-musl.txt

@@ -5,6 +5,7 @@ AIO_ALLDONE
 AIO_CANCELED
 AIO_NOTCANCELED
 BOOT_TIME
+CLONE_NEWTIME
 DEAD_PROCESS
 EMPTY
 Elf32_Chdr

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

@@ -995,6 +995,8 @@ pub const XDP_PKT_CONTD: crate::__u32 = 1 << 0;
 pub const _CS_V6_ENV: c_int = 1148;
 pub const _CS_V7_ENV: c_int = 1149;
 
+pub const CLONE_NEWTIME: c_int = 0x80;
+
 cfg_if! {
     if #[cfg(target_arch = "s390x")] {
         pub const POSIX_FADV_DONTNEED: c_int = 6;