Fixed incorrect OS detection

src/config/config.go

@@ -27,7 +27,7 @@ var (
 	TargetArch string
 
 	// Target platform.
-	TargetOS string
+	TargetOS OS
 )
 
 // Reset resets the configuration to its default values.
@@ -36,9 +36,14 @@ func Reset() {
 	ConstantFold = true
 	Dry = false
 	TargetArch = runtime.GOARCH
-	TargetOS = runtime.GOOS
+	TargetOS = Unknown
 
-	if TargetOS == "darwin" {
-		TargetOS = "mac"
+	switch runtime.GOOS {
+	case "linux":
+		TargetOS = Linux
+	case "darwin":
+		TargetOS = Mac
+	case "windows":
+		TargetOS = Windows
 	}
 }

src/config/os.go

@@ -0,0 +1,10 @@
+package config
+
+type OS uint8
+
+const (
+	Unknown OS = iota
+	Linux
+	Mac
+	Windows
+)