BUILD_DEPENDS= ${PKGNAMEPREFIX}${PORTNAME}>=0:x11/${PKGNAMEPREFIX}${PORTNAME}

% portlint
WARN: Makefile: no port directory /usr/ports/x11/${PKGNAMEPREFIX}clx found, even though it is listed in BUILD_DEPENDS.

This patch ensures that all variables in a *_DEPENDS value are expanded.