add error-pattern in the test

Signed-off-by: xizheyin <[email protected]>

Author: xizheyin

tests/ui/emit-warning-while-exe-and-print-link-info.rs

@@ -1,2 +1,4 @@
 //@ compile-flags: --print native-static-libs --crate-type staticlib  --emit metadata
 //@ check-pass
+//@ error-pattern: warning: skipping link step due to conflict: cannot output linkage information without emitting executable
+//@ error-pattern: note: consider emitting executable to print linkage information