Add test for malloc

test/owic/stdlib/malloc_aligned.c

@@ -0,0 +1,26 @@
+#include <owi.h>
+#include <stdlib.h>
+
+void arbitrary_pre_align() {
+    int s = owi_i32();
+    int m = (s < 8) ? s : 7;
+    for (int i = 0; i < m; i++) {
+        malloc(1);
+    }
+}
+
+int main() {
+    malloc(1024);
+    arbitrary_pre_align();
+    for (int p = 0; p < 10; p++) {
+        int low_pow = (1 << p);
+        for (int i = low_pow; i < 2*low_pow; i++) {
+            void * ptr = malloc(i);
+            if (low_pow < 16) {
+                owi_assert((int) ptr % low_pow == 0);
+            } else {
+                owi_assert((int) ptr % 16 == 0);
+            }
+        }
+    }
+}