srcpkgs: use "nocross=yes" where applicable.

srcpkgs/cross-i686-pc-linux-gnu/template

@@ -28,6 +28,7 @@ checksum="
  ed4dfd9f56b7c82e9c71331bbf8d2ea01ddfddc1b6209bd3f3c8640aa24065cf"
 
 lib32disabled=yes
+nocross=yes
 only_for_archs="x86_64"
 create_wrksrc=yes
 hostmakedepends="perl flex"
@@ -35,10 +36,6 @@ makedepends="zlib-devel gmp-devel mpfr-devel libmpc-devel"
 depends="${pkgname}-libc-${version}_${revision}"
 nostrip_files="libgcc.a libgcov.a libgcc_eh.a"
 
-if [ "$CROSS_BUILD" ]; then
-	msg_error "${pkgname}-${version}: cannot be cross compiled.\n"
-fi
-
 _apply_patch() {
 	local pname="$(basename $1)"