How do I have a comma inside braces inside a macro argument when parentheses cause a syntax error?

I've defined a few macros that make it simpler to define an array of structures, but I can't find a way to use them without generating errors. Here are the macros (and a few example structures to demonstrate why the macros might be used (the actual structures I'm populating are a little more complex)):

struct string_holder {
    const char *string;
};
struct string_array_holder {
    struct string_holder *holders;
};
#define DEFINE_STRING_ARRAY_HOLDER(name, values) \
    static struct string_holder name##__array[] = values; \
    static struct string_array_holder name = { name##__array }
#define WRAP_STRING(string) { string }

It works just fine when you use it to declare an array with one item:

DEFINE_STRING_ARRAY_HOLDER(my_string_array_holder, {
    WRAP_STRING("my string")
});

But when I use multiple items:

DEFINE_STRING_ARRAY_HOLDER(my_string_array_holder, {
    WRAP_STRING("hello"),
    WRAP_STRING("world")
});

I get this error:

error: too many arguments provided to function-like macro invocation

So it's interpreting the comma in the braces as an argument separator. I follow the advice from this question and put parentheses around the problematic argument:

DEFINE_STRING_ARRAY_HOLDER(my_string_array_holder, ({
    WRAP_STRING("hello"),
    WRAP_STRING("world")
}));

Now when I try to compile it, it interprets ({ ... }) as a statement expression and complains:

warning: use of GNU statement expression extension
(a bunch of sy