Remove -Z flag for suppressing validation mismatch ICE

Author: ecstatic-morse

src/librustc/session/config.rs

@@ -1373,8 +1373,6 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         "describes how to render the `rendered` field of json diagnostics"),
     unleash_the_miri_inside_of_you: bool = (false, parse_bool, [TRACKED],
         "take the breaks off const evaluation. NOTE: this is unsound"),
-    suppress_const_validation_back_compat_ice: bool = (false, parse_bool, [TRACKED],
-        "silence ICE triggered when the new const validator disagrees with the old"),
     osx_rpath_install_name: bool = (false, parse_bool, [TRACKED],
         "pass `-install_name @rpath/...` to the macOS linker"),
     sanitizer: Option<Sanitizer> = (None, parse_sanitizer, [TRACKED],