www/phpmyfaq: actually make this work with PHP >= 8.0

I used the wrong poudriere script to test these changes, it builds
with my production settings, where PHP is still set to 7.4, so it
didn't catch the build error.

PR:		261617

www/phpmyfaq/Makefile

@@ -13,7 +13,7 @@ LICENSE=	MPL20
 WRKSRC=		${WRKDIR}/${PORTNAME}
 
 USES=		cpe php:web
-USE_PHP=	filter json mysqli pcre pdf session xml xmlrpc xmlwriter zlib
+USE_PHP=	filter json mysqli pcre session xml xmlrpc xmlwriter zlib
 FAQ_DIR=	attachments data images inc pdf xml
 NO_BUILD=	YES
 NO_ARCH=	YES
@@ -25,4 +25,10 @@ do-install:
 	@${MKDIR} ${STAGEDIR}${WWWDIR}/${i}
 .endfor
 
-.include <bsd.port.mk>
+.include <bsd.port.pre.mk>
+
+.if ${PHP_VER} < 80
+USE_PHP+=	pdf
+.endif
+
+.include <bsd.port.post.mk>