Add FUTEX_LOCK_PI2 on Linux

Author: rtzoeller

libc-test/semver/linux.txt

@@ -599,6 +599,7 @@ FUTEX_CMP_REQUEUE
 FUTEX_CMP_REQUEUE_PI
 FUTEX_FD
 FUTEX_LOCK_PI
+FUTEX_LOCK_PI2
 FUTEX_PRIVATE_FLAG
 FUTEX_REQUEUE
 FUTEX_TRYLOCK_PI

src/unix/linux_like/linux/mod.rs

@@ -3074,6 +3074,7 @@ pub const FUTEX_WAIT_BITSET: ::c_int = 9;
 pub const FUTEX_WAKE_BITSET: ::c_int = 10;
 pub const FUTEX_WAIT_REQUEUE_PI: ::c_int = 11;
 pub const FUTEX_CMP_REQUEUE_PI: ::c_int = 12;
+pub const FUTEX_LOCK_PI2: ::c_int = 13;
 
 pub const FUTEX_PRIVATE_FLAG: ::c_int = 128;
 pub const FUTEX_CLOCK_REALTIME: ::c_int = 256;