Reenable opt-level 3

This comment is quite old, let's see what would happen with current MSVC.

Author: ishitatsuyuki

src/Cargo.toml

@@ -21,14 +21,6 @@ exclude = [
   "tools/rls",
 ]
 
-# Curiously, compiletest will segfault if compiled with opt-level=3 on 64-bit
-# MSVC when running the compile-fail test suite when a should-fail test panics.
-# But hey if this is removed and it gets past the bots, sounds good to me.
-[profile.release]
-opt-level = 2
-[profile.bench]
-opt-level = 2
-
 # These options are controlled from our rustc wrapper script, so turn them off
 # here and have them controlled elsewhere.
 [profile.dev]