split test utils for c

src/Layout-test-utils.h

@@ -0,0 +1,8 @@
+
+#include "Layout.h"
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+
+void test(const char *name, css_node_t *style, css_node_t *expected_layout);
+css_dim_t measure(void *context, css_measure_type_t type, float width);