pubkey_load: replace ARG_CHECK with VERIFY_CHECK

This change prepares for the addition of ge_from_bytes and ge_to_bytes which do
not take a context. This change should be inconsequential because it's very
unlikely to land in the `sizeof(secp256k1_ge_storage) != 64` branch and the
other branch does not have an ARG_CHECK either.

src/secp256k1.c

@@ -247,8 +247,11 @@ static int secp256k1_pubkey_load(const secp256k1_context* ctx, secp256k1_ge* ge,
     } else {
         /* Otherwise, fall back to 32-byte big endian for X and Y. */
         secp256k1_fe x, y;
-        ARG_CHECK(secp256k1_fe_set_b32_limit(&x, pubkey->data));
-        ARG_CHECK(secp256k1_fe_set_b32_limit(&y, pubkey->data + 32));
+        int ret = 1;
+
+        ret &= secp256k1_fe_set_b32_limit(&x, pubkey->data);
+        ret &= secp256k1_fe_set_b32_limit(&y, pubkey->data + 32);
+        VERIFY_CHECK(ret);
         secp256k1_ge_set_xy(ge, &x, &y);
     }
     ARG_CHECK(!secp256k1_fe_is_zero(&ge->x));