Only disable trace! but allow debug! with debug asserts off

Author: oli-obk

src/librustc_driver/Cargo.toml

@@ -12,7 +12,7 @@ crate-type = ["dylib"]
 [dependencies]
 lazy_static = "1.0"
 libc = "0.2"
-log = { package = "tracing", version = "0.1.19" }
+log = { package = "tracing", version = "0.1.19", features = ["release_max_level_debug"] }
 tracing-subscriber = { version = "0.2.11", default-features = false, features = ["fmt", "env-filter", "smallvec", "parking_lot", "ansi"] }
 rustc_middle = { path = "../librustc_middle" }
 rustc_ast_pretty = { path = "../librustc_ast_pretty" }