capnproto: make cross-compilation work

srcpkgs/capnproto/template

@@ -1,7 +1,7 @@
 # Template file for 'capnproto'
 pkgname=capnproto
 version=0.6.1
-revision=3
+revision=4
 wrksrc="${pkgname}-c++-${version}"
 build_style=gnu-configure
 short_desc="Cap'n Proto serialization/RPC system"
@@ -10,7 +10,11 @@ license="MIT"
 homepage="https://capnproto.org"
 distfiles="${homepage}/capnproto-c++-${version}.tar.gz"
 checksum=8082040cd8c3b93c0e4fc72f2799990c72fdcf21c2b5ecdae6611482a14f1a04
-nocross="Tries to execute compiled code during build"
+
+if [ -n "$CROSS_BUILD" ]; then
+	hostmakedepends="capnproto-devel"
+	configure_args="--with-external-capnp"
+fi
 
 post_install() {
 	 vlicense LICENSE.txt