Force LLVM IR verification in test

Author: nikic

tests/ui/linkage-attr/common-linkage-non-zero-init.rs

@@ -2,6 +2,7 @@
 //@ failure-status: 101
 //@ known-bug: #109681
 //@ ignore-wasm32 this appears to SIGABRT on wasm, not fail cleanly
+//@ compile-flags: -Z verify-llvm-ir
 
 // This test verifies that we continue to hit the LLVM error for common linkage with non-zero
 // initializers, since it generates invalid LLVM IR.