[libc++] allow redefined macro in non_trivial_copy_move_ABI test

__config defines _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
on FreeBSD, which conflicts with a command-line definition used by the
non_trivial_copy_move_ABI test.

Add -Wno-macro-redefined to ADDITIONAL_COMPILE_FLAGS in this test.

Reviewed By: philnik

Differential Revision: https://reviews.llvm.org/D141774

libcxx/test/libcxx/utilities/utility/pairs/pairs.pair/non_trivial_copy_move_ABI.pass.cpp

@@ -17,6 +17,7 @@
 // Test that we provide the non-trivial copy operations when _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
 // is specified.
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR
+// ADDITIONAL_COMPILE_FLAGS: -Wno-macro-redefined
 
 #include <utility>
 #include <type_traits>