srcpkgs: use "nocross=yes" where applicable.

srcpkgs/cross-i686-linux-musl/template

@@ -28,6 +28,7 @@ checksum="
  dac94112b9a22d2657cd3f36ca0d62ee1eb10707a22bfc97d5746147ef92852b"
 
 lib32disabled=yes
+nocross=yes
 create_wrksrc=yes
 hostmakedepends="perl flex"
 makedepends="libfl-devel zlib-devel gmp-devel mpfr-devel libmpc-devel"
@@ -35,10 +36,6 @@ nostrip_files="libgcc.a libgcov.a libgcc_eh.a"
 depends="${pkgname}-libc-${version}_${revision}"
 only_for_archs="i686 x86_64 x86_64-musl"
 
-if [ "$CROSS_BUILD" ]; then
-	msg_error "${pkgname}-${version}: cannot be cross compiled.\n"
-fi
-
 _apply_patch() {
 	local pname="$(basename $1)"