[Test] Make sure generic_casts_objc.swift tests an unoptimized build of the test even when --test-optimized is passed.

rdar://problem/56339727

Author: mikeash

Diff for: test/Interpreter/generic_casts_objc.swift

@@ -1,4 +1,6 @@
-// RUN: %target-run-simple-swift | %FileCheck --check-prefix CHECK --check-prefix CHECK-ONONE --dump-input fail %s
+// RUN: %empty-directory(%t)
+// RUN: %target-build-swift -Onone %s -o %t/a.out
+// RUN: %target-run %t/a.out | %FileCheck --check-prefix CHECK --check-prefix CHECK-ONONE %s
 // RUN: %target-build-swift -O %s -o %t/a.out.optimized
 // RUN: %target-codesign %t/a.out.optimized
 // RUN: %target-run %t/a.out.optimized | %FileCheck %s