<NME> build.rs
<BEF> ADDFILE
<MSG> anvil: properly document logind support

<DFF> @@ -0,0 +1,10 @@
+use std::env::var;
+
+fn main() {
+    if !var("CARGO_FEATURE_LOGIND").ok().is_some() {
+        println!("cargo:warning=You are compiling anvil without logind support.");
+        println!("cargo:warning=This means that you'll likely need to run it as root if you want to launch it from a tty.");
+        println!("cargo:warning=To enable logind support add `--feature logind` to your cargo invocation:");
+        println!("cargo:warning=$ cd anvil; cargo run --feature logind");
+    }
+}

anvil: properly document logind support