Update core:sync/sync2 to have a generic Futex interface, and implement the calls appropriately for each platform

core/sync/sync2/futex_windows.odin

@@ -0,0 +1,41 @@
+//+private
+//+build windows
+package sync2
+
+import "core:time"
+
+foreign import Synchronization "system:Synchronization.lib"
+
+@(default_calling_convention="c")
+foreign Synchronization {
+	WaitOnAddress :: proc(Address: rawptr, CompareAddress: rawptr, AddressSize: uint, dwMilliseconds: u32) -> b32 ---
+	WakeByAddressSingle :: proc(Address: rawptr) ---
+	WakeByAddressAll :: proc(Address: rawptr) ---
+}
+
+_futex_wait :: proc(f: ^Futex, expect: u32) -> Futex_Error {
+	expect := expect
+	ms :: ~u32(0) // infinite
+	ok := WaitOnAddress(f, &expect, size_of(expect), ms)
+	return nil if ok else .Timed_Out
+}
+
+_futex_wait_with_timeout :: proc(f: ^Futex, expect: u32, duration: time.Duration) -> Futex_Error {
+	expect := expect
+	
+	ms: u32 = 0
+	if duration >= 0 {
+		ms = u32(u64(duration)/1e6)
+	}
+	
+	ok := WaitOnAddress(f, &expect, size_of(expect), ms)
+	return nil if ok else .Timed_Out
+}
+
+_futex_wake_single :: proc(f: ^Futex) {
+	WakeByAddressSingle(f)
+}
+
+_futex_wake_all :: proc(f: ^Futex) {
+	WakeByAddressAll(f)
+}