Address -Wuninitialized-const-pointer with Clang 21 (#2155)

Author: eramongodb

src/libbson/tests/test-bcon-extract.c

@@ -33,9 +33,9 @@ test_double(void)
 static void
 test_decimal128(void)
 {
-   bson_decimal128_t val;
-   bson_decimal128_t dec;
-   bson_t *bcon;
+   bson_decimal128_t val = {0};
+   bson_decimal128_t dec = {0};
+   bson_t *bcon = NULL;
 
    bson_decimal128_from_string("12", &dec);
    bcon = BCON_NEW("foo", BCON_DECIMAL128(&dec));