add osx support

core/time/tsc_darwin.odin

@@ -0,0 +1,23 @@
+//+private
+//+build darwin
+package time
+
+import "core:sys/darwin"
+
+_get_tsc_frequency :: proc "contextless" () -> u64 {
+	@(static) frequency : u64 = 0
+	if frequency > 0 {
+		return frequency
+	}
+
+	tmp_freq : u64 = 0
+	tmp_size : i64 = size_of(tmp_freq)
+	ret := darwin.syscall_sysctlbyname("machdep.tsc.frequency", &tmp_freq, &tmp_size, nil, 0)
+	if ret < 0 {
+		frequency = 1
+		return 0
+	}
+
+	frequency = tmp_freq
+	return frequency
+}