Remove MIR unsafe check

This also remove safety information from MIR.

tests/ui/asm/x86_64/goto.rs

@@ -1,8 +1,6 @@
 //@ only-x86_64
 //@ run-pass
 //@ needs-asm-support
-//@ revisions: mirunsafeck thirunsafeck
-//@ [thirunsafeck]compile-flags: -Z thir-unsafeck
 
 #![deny(unreachable_code)]
 #![feature(asm_goto)]

tests/ui/asm/x86_64/goto.stderr

@@ -1,5 +1,5 @@
 warning: unreachable statement
-  --> $DIR/goto.rs:99:9
+  --> $DIR/goto.rs:97:9
    |
 LL | /         asm!(
 LL | |             "jmp {}",
@@ -13,7 +13,7 @@ LL |           unreachable!();
    |           ^^^^^^^^^^^^^^ unreachable statement
    |
 note: the lint level is defined here
-  --> $DIR/goto.rs:89:8
+  --> $DIR/goto.rs:87:8
    |
 LL | #[warn(unreachable_code)]
    |        ^^^^^^^^^^^^^^^^

tests/ui/asm/x86_64/goto.thirunsafeck.stderr

@@ -1,23 +0,0 @@
-warning: unreachable statement
-  --> $DIR/goto.rs:99:9
-   |
-LL | /         asm!(
-LL | |             "jmp {}",
-LL | |             label {
-LL | |                 return;
-LL | |             },
-LL | |             options(noreturn)
-LL | |         );
-   | |_________- any code following this expression is unreachable
-LL |           unreachable!();
-   |           ^^^^^^^^^^^^^^ unreachable statement
-   |
-note: the lint level is defined here
-  --> $DIR/goto.rs:89:8
-   |
-LL | #[warn(unreachable_code)]
-   |        ^^^^^^^^^^^^^^^^
-   = note: this warning originates in the macro `unreachable` (in Nightly builds, run with -Z macro-backtrace for more info)
-
-warning: 1 warning emitted
-