security/theonionbox: Spell post-install correctly

Install rc script with executable permissions again after r501220.

security/theonionbox/Makefile

@@ -2,6 +2,7 @@
 
 PORTNAME=	theonionbox
 DISTVERSION=	4.3.1
+PORTREVISION=	1
 CATEGORIES=	security net python
 MASTER_SITES=	CHEESESHOP
 
@@ -42,7 +43,7 @@ post-patch:
 post-patch-DOCS-off:
 	@${REINPLACE_CMD} "s|('share/doc/${PORTNAME}', \['docs/\*\.\*'\]),||" ${WRKSRC}/setup.py
 
-xpost-install:
+post-install:
 	@${CHMOD} +x ${STAGEDIR}${PREFIX}/etc/rc.d/${PORTNAME}
 
 correct-plist: