Add ENOATTR for Android

[mati865]

PR based on #594

It's defined in Android sysroot so it should work without test workaround (CI should catch it otherwise?).

[rust-highfive]

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[mati865]

cargo:warning=/checkout/target/x86_64-linux-android/debug/build/libc-test-a83d36f94edd2cc5/out/main.c:17374:51: error: 'ENOATTR' undeclared here (not in a function)
cargo:warning=             static int __test_const_ENOATTR_val = ENOATTR;
cargo:warning=                                                   ^

Apparently tests fail without workaround.

[alexcrichton]

@bors: r+

[bors]

📌 Commit 27043ec has been approved by alexcrichton

[bors]

⌛ Testing commit 27043ec with merge 4dd6665...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing 4dd6665 to master...