Fix simple test on platforms where compaction is not supported

844588f9157b364244a7d34ee0fcc70ccc2a7dd9 made it so that trying to call
gc_verify_compaction_references on unsupported platform result in an
exception rather than a crash. Rescue the exception in a YJIT btest
that uses gc_verify_compaction_references.

bootstraptest/test_yjit.rb

@@ -662,7 +662,11 @@ assert_equal "good", %q{
   foo
   foo
 
+  begin
     GC.verify_compaction_references(double_heap: true, toward: :empty)
+  rescue NotImplementedError
+    # in case compaction isn't supported
+  end
 
   foo
 }