rustc_llvm: Link to zlib on dragonfly

Author: Alex Zepeda

compiler/rustc_llvm/build.rs

@@ -251,7 +251,8 @@ fn main() {
     } else if target.contains("windows-gnu") {
         println!("cargo:rustc-link-lib=shell32");
         println!("cargo:rustc-link-lib=uuid");
-    } else if target.contains("haiku") || target.contains("darwin") {
+    } else if target.contains("haiku") || target.contains("darwin") || target.contains("dragonfly")
+    {
         println!("cargo:rustc-link-lib=z");
     } else if target.contains("netbsd") {
         println!("cargo:rustc-link-lib=z");