Add the meson MODULE.

It's still a bit rough around the edges but allows me to build the upcoming
libhttpseverywhere port.

devel/meson/meson.port.mk

@@ -0,0 +1,39 @@
+# $OpenBSD: meson.port.mk,v 1.1 2017/04/08 13:29:22 ajacoutot Exp $
+
+BUILD_DEPENDS +=	devel/meson>=0.39.1
+SEPARATE_BUILD ?=	Yes
+
+MODMESON_WANTCOLOR ?=	No
+.if ${MODMESON_WANTCOLOR:L} == "no"
+CONFIGURE_ENV += TERM="dumb"
+.endif
+
+.if empty(CONFIGURE_STYLE)
+CONFIGURE_STYLE=	meson
+.endif
+
+.if ! empty(INSTALL_STRIP)
+CONFIGURE_ARGS +=	--strip
+.endif
+
+MODMESON_configure=	${SETENV} CC="${CC}" CFLAGS="${CFLAGS}" CXX="${CXX}" \
+				CXXFLAGS="${CXXFLAGS}" LDFLAGS="${LDFLAGS}" \
+				LC_CTYPE="en_US.UTF-8" ${CONFIGURE_ENV} \
+				${LOCALBASE}/bin/meson --buildtype=plain \
+				--prefix "${PREFIX}" ${CONFIGURE_ARGS} \
+				${WRKSRC} ${WRKBUILD}
+
+.if !target(do-build)
+do-build:
+	${LOCALBASE}/bin/ninja -C ${WRKBUILD} -v -j ${MAKE_JOBS}
+.endif
+
+.if !target(do-install)
+do-install:
+	${LOCALBASE}/bin/ninja -C ${WRKBUILD} ${FAKE_TARGET}
+.endif
+
+.if !target(do-test)
+do-test:
+	${LOCALBASE}/bin/ninja -C ${WRKBUILD} ${TEST_TARGET}
+.endif