helpers: add io_uring_calloc helper

add io_uring_calloc() helper, and replace
all calloc() with io_uring_calloc() in all tests.

Signed-off-by: Zhiqiang Liu <[email protected]>
diff --git a/test/helpers.c b/test/helpers.c
index 83ed3e5..af6d936 100644
--- a/test/helpers.c
+++ b/test/helpers.c
@@ -28,3 +28,17 @@
 	ret = posix_memalign(memptr, alignment, size);
 	assert(!ret);
 }
+
+/*
+ * Helper for allocating space for an array of nmemb elements
+ * with size bytes for each element.
+ */
+void *io_uring_calloc(size_t nmemb, size_t size)
+{
+	void *ret;
+	ret = calloc(nmemb, size);
+	assert(ret);
+	return ret;
+}
+
+