libcore/num: Remove unused macro argument.

[nodakai]

No description provided.

[rust-highfive]

r? @brson

(rust_highfive has picked a reviewer for you, use r? to override)

[hanna-kruppe]

This is not the first macro to end up with an unused argument. It's not even the first one in libcore/num! Makes me wonder if an unused arguments lint for macros is a good idea (if it's even possible).

[alexcrichton]

@bors: r+ e03cea4

Thanks!

[bors]

⌛ Testing commit e03cea4 with merge 7a737d5...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-debug-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-linux-cross-opt, auto-linux-musl-64-opt, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-mac-ios-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