Fix backtrace UI test when panic=abort is used

src/test/ui/backtrace.rs

@@ -43,6 +43,7 @@ fn expected(fn_name: &str) -> String {
     format!(" backtrace::{}", fn_name)
 }
 
+#[cfg(not(panic = "abort"))]
 fn contains_verbose_expected(s: &str, fn_name: &str) -> bool {
     // HACK(eddyb) work around the fact that verbosely demangled stack traces
     // (from `RUST_BACKTRACE=full`, or, as is the case here, panic-in-panic)