cw_kvstore_add works now

fixed a bug in mavl_add

FossilOrigin-Name: 4b040305182ef40f6f053fe1d84ea15f533e931c9d665b513b9a644592519f3e

src/cw/cw_strdup.c

@@ -0,0 +1,10 @@
+#include <string.h>
+#include <stdlib.h>
+
+char *cw_strdup(const char *s) {
+    size_t size = strlen(s) + 1;
+    char *p = malloc(size);
+    if (p) 
+        memcpy(p, s, size);
+    return p;
+}