Implemented function calls

src/build/asm/Mnemonic.go

@@ -7,6 +7,8 @@ const (
 	MOVE
 	RETURN
 	SYSCALL
+	LABEL
+	CALL
 )
 
 // String returns a human readable version.
@@ -20,6 +22,12 @@ func (m Mnemonic) String() string {
 
 	case SYSCALL:
 		return "syscall"
+
+	case LABEL:
+		return "label"
+
+	case CALL:
+		return "call"
 	}
 
 	return "NONE"