Revert "[interop] test - do not run index-while-building libc++ test on SDKs with Foundation broken in C++ interop mode"

This reverts commit be0f25d.

Author: hyp

test/Interop/Cxx/symbolic-imports/indexing-emit-libcxx-symbolic-module-interface.swift

@@ -13,7 +13,6 @@
 // RUN: ls %t/store/interfaces | %FileCheck --check-prefix=FILES %s
 
 // REQUIRES: OS=macosx
-// REQUIRES: cxx-interop-fixed-cf_options
 
 //--- Inputs/module.modulemap
 module CxxModule {