vietnamese/x-unikey: Fix build with Clang 6

data.cpp💯15: error: constant expression evaluates to -72 which cannot be narrowed to type 'unsigned char' [-Wc++11-narrowing]
{{'A','a','<B8>','<B8>','<B5>','<B5>','<B6>','<B6>','<B7>','<B7>','<B9>','<B9>',      // 0: a
                 ^~~~~~

http://beefy11.nyi.freebsd.org/data/head-i386-default/p477696_s338122/logs/errors/vi-x-unikey-1.0.4.log

- While here prevent build from asking an interactive question
  during the install phase

vietnamese/x-unikey/Makefile

@@ -9,10 +9,13 @@ MASTER_SITES=	SF/unikey/${PORTNAME}/${PORTVERSION}
 MAINTAINER=	ports@FreeBSD.org
 COMMENT=	Vietnamese input method for X
 
-USES=		tar:bzip2
+USES=		compiler tar:bzip2
 USE_XORG=	x11
 GNU_CONFIGURE=	yes
 
+CXXFLAGS+=	${CXXFLAGS_${CHOSEN_COMPILER_TYPE}}
+CXXFLAGS_clang=	-Wno-c++11-narrowing
+
 PLIST_FILES=	bin/unikey bin/ukxim
 
 .include <bsd.port.mk>

vietnamese/x-unikey/files/patch-src_xim_install.sh

@@ -0,0 +1,10 @@
+Do not ask an interactive question during the install phase.
+
+--- src/xim/install.sh.orig	2018-08-25 14:18:57 UTC
++++ src/xim/install.sh
+@@ -1,4 +1,5 @@
+ #!/bin/sh
++exit 0
+ echo 
+ echo "To use UniKey, certain environment variables must be set."
+ echo "Do you want to set these variables in /etc/profile? (y/N)"