Add some examples for the print! macro

[steveklabnik]

No description provided.

[rust-highfive]

r? @alexcrichton

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[alexcrichton]

Do these doc examples pass? I'd expect the unused_must_use lint to trigger on not handling the return value from flush(). If it's passing now (or if it starts passing later) r=me though, thanks!

[steveklabnik]

Hmm, I thought I ran the tests, but maybe I missed macros.

[steveklabnik]

@bors: r=alexcrichton rollup

[bors]

📌 Commit d9819b7 has been approved by alexcrichton

[bors]

⌛ Testing commit d9819b7 with merge ab792ab...

[bors]

💔 Test failed - auto-win-msvc-32-opt

[steveklabnik]

@bors: retry

[bors]

⚡ Previous build results for auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt are reusable. Rebuilding only auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt