Auto merge of #37867 - brson:no-lexer-verify, r=alexcrichton

Don't build the lexer verifier during tidy

Tidy is not the right place to do this. Tidy is for running lints.
We should instead be running the lexer/grammar tests as part of the test
suite.

This may fix nightly breakage, but I don't understand why.

https://buildbot.rust-lang.org/builders/nightly-dist-rustc-linux/builds/715/steps/distcheck/logs/stdio

r? @alexcrichton

cc @dns2utf8