[gn build] Port e43e8ec

Author: llvmgnsyncbot

llvm/utils/gn/secondary/libcxx/include/BUILD.gn

@@ -1492,7 +1492,6 @@ if (current_toolchain == default_toolchain) {
       "__type_traits/is_member_pointer.h",
       "__type_traits/is_nothrow_assignable.h",
       "__type_traits/is_nothrow_constructible.h",
-      "__type_traits/is_nothrow_convertible.h",
       "__type_traits/is_nothrow_destructible.h",
       "__type_traits/is_null_pointer.h",
       "__type_traits/is_object.h",