Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/wasi-common/winx/src/time.rs

@@ -0,0 +1,10 @@
+use cvt::cvt;
+use winapi::um::{profileapi::QueryPerformanceFrequency, winnt::LARGE_INTEGER};
+
+pub fn perf_counter_frequency() -> std::io::Result<u64> {
+    unsafe {
+        let mut frequency: LARGE_INTEGER = std::mem::zeroed();
+        cvt(QueryPerformanceFrequency(&mut frequency))?;
+        Ok(*frequency.QuadPart() as u64)
+    }
+}