fix: skip first arg to set command line as expected by interpreted main (#203)

_test/flag0.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+)
+
+func main() {
+	flag.Parse()
+	fmt.Println("Narg:", flag.NArg())
+}
+
+// Output:
+// Narg: 0

yaegi.go

@@ -46,6 +46,8 @@ func main() {
 	}
 
 	if len(args) > 0 {
+		// Skip first os arg to set command line as expected by interpreted main
+		os.Args = os.Args[1:]
 		b, err := ioutil.ReadFile(args[0])
 		if err != nil {
 			log.Fatal("Could not read file: ", args[0])