Print IR before optimization

This makes invalid IR easier to spot (see previous commit).

tgo.go

@@ -424,6 +424,10 @@ func Compile(inpath, outpath, target string, printIR bool) error {
 		return err
 	}
 
+	if printIR {
+		fmt.Println(c.IR())
+	}
+
 	if err := c.Verify(); err != nil {
 		return err
 	}
@@ -432,10 +436,6 @@ func Compile(inpath, outpath, target string, printIR bool) error {
 		return err
 	}
 
-	if printIR {
-		fmt.Println(c.IR())
-	}
-
 	err = c.EmitObject(outpath)
 	if err != nil {
 		return err