tree-sitter: cross build fails with Rust 1.57.0.

Per [1], a default hash builder only exits for std builds. This is
checked in [2], and that test is currently failing for us.

We don't want to fix it with the environment variable, because the
autocfg tests should be working.

[1] 0af3c466a7/src/map.rs (L70)
[2] 0af3c466a7/build.rs (L4)

srcpkgs/tree-sitter/template

@@ -11,6 +11,7 @@ homepage="https://tree-sitter.github.io"
 distfiles="https://github.com/tree-sitter/tree-sitter/archive/v${version}.tar.gz"
 checksum=2a0445f8172bbf83db005aedb4e893d394e2b7b33251badd3c94c2c5cc37c403
 make_check=no # tests require generating fixtures from remote repositories
+nocross=yes # fails with current rust
 
 post_build() {
 	# Build libtree-sitter, since do_build builds the tree-sitter CLI.