Auto merge of #1038 - Amanieu:fix_netbsd, r=alexcrichton

Fix netbsd build with "stdbuild"

A bug was introduced in #930 which caused netbsd to not link to libm.

r? @alexcrichton

ci/run.sh

@@ -86,5 +86,9 @@ if [ "$TARGET" = "x86_64-unknown-linux-gnux32" ]; then
   opt="--release"
 fi
 
-cargo test $opt --no-default-features --manifest-path libc-test/Cargo.toml --target $TARGET
+# Building with --no-default-features is currently broken on rumprun because we
+# need cfg(target_vendor), which is currently unstable.
+if [ "$TARGET" != "x86_64-rumprun-netbsd" ]; then
+  cargo test $opt --no-default-features --manifest-path libc-test/Cargo.toml --target $TARGET
+fi
 exec cargo test $opt --manifest-path libc-test/Cargo.toml --target $TARGET

src/unix/mod.rs

@@ -306,11 +306,11 @@ cfg_if! {
     } else if #[cfg(target_os = "emscripten")] {
         #[link(name = "c")]
         extern {}
-    } else if #[cfg(all(target_os = "netbsd"))] {
+    } else if #[cfg(all(target_os = "netbsd",
+                        feature = "stdbuild", target_vendor = "rumprun"))] {
         // Since we don't use -nodefaultlibs on Rumprun, libc is always pulled
         // in automatically by the linker. We avoid passing it explicitly, as it
         // causes some versions of binutils to crash with an assertion failure.
-        #[cfg_attr(feature = "stdbuild", cfg(target_vendor = "rumprun"))]
         #[link(name = "m")]
         extern {}
     } else if #[cfg(any(target_os = "macos",