lang/rust-nightly: Fix check-plist same as lang/rust 1.35.0

Avoid staging the local copy of LLVM into ${STAGEDIR}${WRKDIR}
during install.

lang/rust-nightly/files/patch-src_bootstrap_native.rs

@@ -0,0 +1,46 @@
+Avoid unnecessarily restarting the LLVM build and installing it
+into STAGEDIR during the install phase.
+
+--- src/bootstrap/native.rs.orig	2019-05-22 05:39:52 UTC
++++ src/bootstrap/native.rs
+@@ -92,17 +92,9 @@ impl Step for Llvm {
+             .join(exe("llvm-config", &*builder.config.build));
+         let done_stamp = out_dir.join("llvm-finished-building");
+ 
+-        if let Some(llvm_commit) = llvm_info.sha() {
+             if done_stamp.exists() {
+-                let done_contents = t!(fs::read(&done_stamp));
+-
+-                // If LLVM was already built previously and the submodule's commit didn't change
+-                // from the previous build, then no action is required.
+-                if done_contents == llvm_commit.as_bytes() {
+-                    return build_llvm_config
+-                }
++                return build_llvm_config
+             }
+-        }
+ 
+         let _folder = builder.fold_output(|| "llvm");
+         let descriptor = if emscripten { "Emscripten " } else { "" };
+@@ -218,6 +210,10 @@ impl Step for Llvm {
+             }
+         }
+ 
++        if target == "powerpc64-unknown-freebsd" {
++            cfg.define("CMAKE_EXE_LINKER_FLAGS", "-Wl,-rpath=/usr/local/lib/%CC% -L/usr/local/lib/%CC%");
++        }
++
+         // http://llvm.org/docs/HowToCrossCompileLLVM.html
+         if target != builder.config.build && !emscripten {
+             builder.ensure(Llvm {
+@@ -283,9 +279,7 @@ impl Step for Llvm {
+ 
+         cfg.build();
+ 
+-        if let Some(llvm_commit) = llvm_info.sha() {
+-            t!(fs::write(&done_stamp, llvm_commit));
+-        }
++        t!(fs::write(&done_stamp, "done building LLVM"));
+ 
+         build_llvm_config
+     }