compiler: add support for $if x32, x64, big_endian, little_endian

vlib/runtime/runtime_win.v

@@ -1 +1,16 @@
 module runtime
+
+import os
+
+fn nr_cpus_win() int {
+	mut nr := int(C.GetCurrentProcessorNumber())
+	if nr == 0 {
+		nr = os.getenv('NUMBER_OF_PROCESSORS').int()
+	}
+	return nr
+}
+
+fn nr_cpus_nix() int {
+	eprintln('nr_cpus_nix should be callable only for nix platforms')
+	return 1
+}