Append .exe to windows builds

Author: juho05

build/build.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"runtime"
 	"strings"
 
 	"github.com/Bananenpro/cli"
@@ -47,6 +48,10 @@ func getOutputName(projectRoot, output string) (string, error) {
 		output = filepath.Base(absRoot)
 	}
 
+	if runtime.GOOS == "windows" {
+		output += ".exe"
+	}
+
 	if stat, err := os.Stat(output); err == nil && stat.IsDir() {
 		return "", cli.Error("'%s' already exists and is a directory. Specify another output name with '-o <name>'.", output)
 	}