zkvm: fix path to cmath in zkvm module

Author: marijanp

library/std/src/sys/pal/zkvm/mod.rs

@@ -12,7 +12,7 @@ const WORD_SIZE: usize = core::mem::size_of::<u32>();
 pub mod alloc;
 #[path = "../zkvm/args.rs"]
 pub mod args;
-#[path = "../unix/cmath.rs"]
+#[path = "../../cmath.rs"]
 pub mod cmath;
 pub mod env;
 #[path = "../unsupported/fs.rs"]