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

vlib/runtime/runtime_nix.v

@@ -0,0 +1,16 @@
+module runtime
+
+fn nr_cpus_nix() int {
+	$if linux {
+		return int(C.sysconf(C._SC_NPROCESSORS_ONLN))
+	}
+	$if mac {
+		return int(C.sysconf(C._SC_NPROCESSORS_ONLN))
+	}
+	return 1
+}
+
+fn nr_cpus_win() int {
+	eprintln('nr_cpus_win should be callable only for windows')
+	return 1
+}